The want ads posted by the anonymous buyer on Armslist.com, a sprawling free classified ads website for guns, telegraphed urgency.

Feb. 20: "Got 250 cash for a good handgun something.reliable."

Feb. 27: "I got 200 250 cashlooking for a good handgun please let me know what u got."

Feb. 28: "Looking to buy some 9 mm ammo and not at a crazy price."

The intentions and background of the prospective buyer were hidden, as is customary on such sites. The person posting these ads, however, left a phone number, enabling The to trace them to their source: Omar Roman-Martinez, 29, of Colorado Springs, Colo., who has a pair of felony convictions for burglary and another for motor vehicle theft, as well as a misdemeanor domestic violence conviction — all of which bar him from having guns. Yet he was so determined that he even offered to trade a tablet computer or a vintage Pepsi machine for firearms.

When questioned in a telephone interview, Roman-Martinez said he ultimately decided not to buy a weapon. He also insisted that a 9-millimeter handgun he posted for sale on the website last month belonged to someone else.

"I’m a felon," he said. "I can’t possess firearms."

The mere fact that Roman-Martinez was seeking to buy and sell guns on Armslist underscores why extending background checks to the growing world of online sales has become a centerpiece of new gun legislation being taken up in the Senate this week. With no requirements for backgroundchecks on most private transactions, a Times examination found, Armslist and similar sites function as unregulated bazaars, where the essential anonymity of the Internet allows unlicensed sellers to advertise scores of weapons and people legally barred from gun ownership to buy them.

The bipartisan Senate compromise under consideration would require that background checks be conducted through federally licensed dealers on all Internet and gun show sales. Gun control advocates argue that such checks might have prevented shootings like that of Zina Haughton, 42, who was killed in October with two other women by her husband, Radcliffe, even though a restraining order barred him from having guns. Haughton simply contacted a private seller on Armslist and handed over $500 in a McDonald’s parking lot for a .40-caliber semiautomatic pistol and three magazines.

Seeking a glimpse into the largely hidden online gun market, The Times assembled a database and analyzed several months of ads from Armslist, which has become the dominant player in the arena, and examined numerous smaller sites.

Over the past three months, The Times identified more than 160,000 gun ads on Armslist. Some were for the same guns, making it difficult to calculate just how many guns were actually for sale. Even so, with more than 20,000 ads posted every week, the number is probably in the tens of thousands.

Notably, 94 percent of the ads were posted by "private parties," who, unlike licensed dealers, are not required to conduct background checks.

Besides Roman-Martinez, the Times investigation led to Gerard Toolin, 46, of Walterboro, S.C., who is a fugitive from the Rhode Island police and has two outstanding felony warrants, as well as a misdemeanor warrant — all barring him from owning guns. He was recently seeking to buy an AK-47 assault rifle on Armslist and was also trying to trade a Marlin rifle. He posted photos to his Facebook account of an AK-47 he had already purchased, along with a variety of other guns.

There was also Martin Fee, who has a domestic battery conviction in Florida and other arrests and convictions in Florida and New Jersey, including for drug possession, burglary and larceny. He was selling a Chinese SKS rifle on classified section of another website, BudsGunShop.com.

The examination of Armslist raised questions about whether many sellers are essentially functioning as unlicensed firearms dealers, in contravention of federal law. The law says that people who "engage in the business" of selling firearms need to obtain a license and conduct background checks on customers. While the definition of engaging in business is vague, The Times found that more than two dozen people had posted more than 20 different guns for sale in a several month span.

Among them was Joshua Lovejoy, 32, who since November has advertised more than 100 guns on Armslist, mostly in Canton, Ohio, ranging from AR-15 assault rifles to Glock 19 semiautomatic pistols. He once listed more than 20 guns in a single ad. He insisted in a telephone interview, however, that he had sold only a few.

Then there was Ron Metz, 49, who has advertised more than 80 guns from Anderson, S.C., since February. Metz said in an interview that he had needed money, so he started selling some guns and trading for others. He also bought other guns, which he turned around and sold as well. He said he had no real idea how many he had sold, guessing that it was more than a dozen. He never keeps any records and does not do any background checks, explaining: "I can just sort of read people."

"You think I broke a law?" he asked.

‘A GUN SHOW THAT NEVER ENDS’

Armslist was the brainchild of Jonathan Gibbon and Brian Mancini, friends who attended the U.S. Air Force Academy and then transferred to the University of Pittsburgh.

Gibbon, who did not respond to requests for comment, said in a 2010 interview with Human Events, a conservative website, that he got the idea for Armslist during the summer of 2007 when he saw that the classifieds website Craigslist.com had decided to ban gun-related ads "because a few users cried out for it." Gibbon, who went on to law school at the University of Oklahoma, where he founded the Second Amendment Club, said he had been inspired to "create a place for law-abiding gun owners to buy and sell online without all of the hassles of auctions and shipping."

Mancini, who designed the site, recently left the company. Gibbon remains the site’s owner, while also practicing law in Pennsylvania, according to his profile on LinkedIn. Armslist LLC, registered with the Oklahoma secretary of state, lists an office suite in Pittsburgh as its business address.

When asked by Human Events to describe the site, Gibbon said: "Imagine a gun show that never ends."

Gun shows have long been a source of concern for gun control advocates and law enforcement officials, because many allow unregulated sales without background checks. Websites make such transactions far more widely available, with just a few clicks of a mouse.

A 2011 undercover investigation by the city of New York examined private party gun sellers on a range of websites, including Armslist, to see whether they would sell guns to someone who said that they probably could not pass a background check. (Federal law bars sales to any person the seller has reason to believe is prohibited from purchasing firearms). Investigators found that 77 of 125 online sellers agreed to sell the weapons anyway.

Armslist posts a disclaimer on its home page, urging users to "comply with local, state, federal and international law," but it also makes clear that the site "does not become involved in transactions between parties."

What the site does do is make it simple for anyone seeking to buy a gun without a background check, enabling users to filter gun ads in their state by ones being sold by private parties.

Federal law places one significant restriction on transactions among private parties, barring people from directly selling guns to people in other states who are not licensed firearms dealers. Licensed dealers must act as intermediaries in transactions across state lines and perform background checks. But an examination of ads on the website shows that illegal interstate transactions can occur.

An ad for a "new in box" Ruger rifle posted on April 1 in Indianapolis stated that if the buyer was out of state, the seller would ship to the buyer’s "front door," "person to private person."

A seller on another ad, posted April 2, in Brighton, Colo., vented about repeated no-shows in his previous attempts to sell the gun, so he made clear, "No more out of state."

Many ads simply require the transactions occur "face to face." Some even provide assurances: "no questions asked" and "no paperwork."

The loose online atmosphere was evident in the case of an Arizona gun dealer, Walter Young, who pleaded guilty last week to a federal gun charge stemming from an investigation into his sale of a .50-caliber rifle, dozens of gun kits and thousands of rounds of ammunition to an anonymous buyer who contacted him on Gunbroker.com.

Young — a Tea Party activist who posted a YouTube video in February suggesting that he was being persecuted for criticizing the government — told federal agents he had shipped everything to an address in Texas near the Mexican border, without even knowing the identity of the recipient, according to court records. After initially lying to investigators, he admitted looking the other way in his online dealings, records show.

"Young stated there was a general ‘don’t ask, don’t tell’ policy in the gun world when it came to wanting to know why a person was purchasing a particular item, and for that reason he did not question people he sold items to," federal prosecutors said in a court filing.

Other cases have had deadly consequences.

In 2011, Dmitry Smirnov, a Canadian resident, contacted Benedict Ladera, from Kent, Wash., via Armslist, expressing interest in a Smith & Wesson .40-caliber pistol that Ladera had posted for sale.

Ladera, who had sold about 20 guns on Armslist over the previous year, agreed to meet at a casino but increased the price of the handgun to $600, from $400, because he was from out of state, according to court records. After buying the gun, Smirnov drove to Chicago, where he stalked Jitka Vesel, a woman he had briefly dated a few years earlier, and on April 13, 2011, shot and killed her. Smirnov turned himself into authorities and was later sentenced to life in prison.

Federal authorities also arrested Ladera, who pleaded guilty to making an illegal transfer of a firearm to a nonstate resident and was sentenced to one year in prison. Last year, the Brady Center to Prevent Gun Violence filed a wrongful-death lawsuit against Armslist on behalf of Vesel’s family.

In the case of Radcliffe Haughton, the Wisconsin man who killed his wife, the person who sold him the gun on Armslist told federal investigators that he had checked Haughton’s driver’s license to make sure he was a Wisconsin resident. He also said he asked Haughton whether he was prohibited from having firearms, but he indicated that he was not.

FEW INTERNET PROSECUTIONS

Despite these cases, it appears that prosecutions of people who illegally buy and sell guns on the Internet are relatively unusual. A review of nearly 100 court cases in which federal authorities seized guns over the last year found that in very few instances were Internet transactions the focus of the investigations.

Identifying the people who buy and sell guns on these online forums is impossible in most cases because the sites protect the anonymity of their users.

On Armslist, potential buyers can contact sellers directly through the website, without making their contact information public. In some cases where people included phone numbers in their ads, The Times tried to trace them — a task made more difficult because most were unlisted cellphones — and determine whether the people had criminal records or other firearms prohibitions.

Many numbers led nowhere. Among the ones that were traceable, most people examined had clean records, or had only misdemeanor convictions that did not disqualify them from having weapons. In some cases that raised questions, it was impossible to conclusively verify identities. But several people emerged who clearly should not be buying or selling guns.

Omar Roman-Martinez spent a little more than a year in prison, getting out in 2010, after pleading guilty to second-degree burglary for breaking into a car with some friends, taking a key and an address, and then going to the person’s house, where they made off with jewelry, a safe and electronics. He had prior felony convictions for burglarizing an auto-parts store and for stealing a car from a car dealership, and a misdemeanor assault conviction for biting and repeatedly using a telephone receiver to hit the woman he was living with, according to court and police records.

Roman-Martinez initially posted general inquiries on Armslist, looking to buy a handgun for cash and then ammunition. He also tried to sell a Jimenez Arms 9-millimeter handgun. In mid-March, he offered to trade a tablet computer that "has the works" for a handgun or pistol grip shotgun. Later he posted an ad offering a "working condition 1970s pepsi machine" for "nice firearms or one nice one." He explained in the ad: "These machines are very wanted and most dont work mine does shot me an offer."

When queried, Roman-Martinez initially acknowledged the ads but tried to sidestep, saying that he had never acquired a gun and that the one he was trying to sell was not his. By the end of the conversation, however, he denied he had anything to do with the ads.

"I’ve heard of Armslist," he said. "Of course, everybody has. I don’t have anything posted on there."

The conversation unfolded similarly with Gerard Toolin, the man with outstanding felony warrants from Rhode Island who is now living in South Carolina. The charges against Toolin, which date to 2002, relate to allegations that he defrauded people through his heating and cooling business. He skipped out on court appearances and fled the state, records show.

He posted an ad on Armslist on April 9, in which he wrote, "I am looking to buy A ak-47." Initially unaware of who was calling, Toolin eagerly explained to a reporter that he already had one and was looking to acquire a second. After the reporter identified himself and asked about his warrants, Toolin said, "Who says I’m buying a weapon for myself?"

But Toolin had also posted several ads in March, seeking to trade a Marlin 336SC rifle for a 12-gauge tactical shotgun — a combat-style weapon. Pictures posted on Toolin’s Facebook page, in which he "likes" Armslist’s Facebook page, made clear that he possessed an array of weapons. He posted a picture of an AK-47 in mid-March, saying: "I would like everyone to welcome the newest member of my family … I adopted her yesterday." Another photo posted in late November showed him loaded down with weapons, including an assault rifle and several pistols strapped to his body. He captioned the snapshot: "I don’t think I have enough maybe one or two more."

When asked about the photographs, Toolin said: "You sure they’re real guns? How do you know they’re not reproductions?"

Minutes after the conversation, he took his Facebook account offline.

The Times also found Martin Fee, of Vero Beach, Fla., while examining a listing for a Chinese SKS rifle on Budsgunshop.com. In the ad, Fee said he would not sell to anyone living in New York, New Jersey or "the People’s Republic of California." A Twitter account belonging to "Marty Fee" of Vero Beach is filled with vitriolic postings about President Barack Obama and liberals, including one that says the president and attorney general "should be chained n shot."

Fee, 45, has an arrest record dating back decades, and it is difficult to verify which charges resulted in convictions. But a domestic battery conviction from 1999, resulting from a dispute between Fee and his then-wife that turned physical, appeared to disqualify him from possessing firearms.

Reached by phone last week, Fee said he had sold the gun and had it shipped to a licensed dealer. When a reporter asked him how he could own a gun with his domestic violence conviction, he backpedaled, insisting that the SKS rifle was not actually his, and that he "posted it up there for a friend of mine."

"I never saw the weapon. I never touched the weapon," he said, declining to identify the friend. He then ended the call.

Shortly thereafter, his ad disappeared from the website.

WHEN IS A ‘SELLER’ A ‘DEALER’?

Under current law, the question of when a background check must occur depends on who is selling the gun. Federal regulations require licensed dealers to perform checks, but the legal definition of who must be licensed is blurry. Regulations define a dealer as a "person who devotes time, attention and labor to dealing in firearms as a regular course of trade or business with the principal objective of livelihood and profit." People engaged in only "occasional sales" for their personal collections, or for a hobby, are exempted.

Precisely how many guns it takes for the "occasional" seller to become a dealer is not specified.

The design of the Armslist site makes it difficult to tie together all of the ads of individual sellers in order to identify the most active. Again, a phone number makes the task easier. Using phone numbers, as well as computer analysis, The Times connected all the ads for some sellers, including Lovejoy, who has advertised scores of guns for sale on Armslist over the past few months. One ad in January listed more than 20 guns, including several AR-15 assault rifles and an array of AMD-65s, a Hungarian variant of the AK-47.

In a telephone interview, Lovejoy, who is a paramedic and is studying to become a nurse, described his buying and selling of guns on Armslist and other sites as a "hobby."

"A lot of times when I get rid of something that I have, I don’t make a penny on it," he said.

Lovejoy said that he always made sure to look at buyers’ driver’s licenses to check that they were Ohio residents and that he would occasionally record a bill of sale, with phone numbers but no names and addresses. He said he supported proposals to require background checks on Internet sales.

"It would give me more peace of mind," he said.

While Lovejoy was willing to discuss his ads with a reporter, other Armslist sellers reacted differently. Noel Lee Velarde, who has advertised more than 30 guns out of Flint, Mich., on Armslist dating back to late January, twice hung up on a reporter.

Bob Vivona, 69, who describes himself as an Army veteran and retired police detective sergeant, has advertised more than 20 guns on Armslist out of Missouri going back to February. Even though it is not required by law, he said, he takes it upon himself to look people’s names up in a statewide online court database. He said he was simply getting rid of guns he had bought but found he did not like, insisting that there was nothing wrong with the number of guns he was selling.

"It’s not an issue," he said. "It’s the Second Amendment."

© 2013 The New York Times Company