LAS VEGAS>> Grab-and-run thefts, craps cheating schemes and inside jobs are ongoing headaches for casinos, according to a top Nevada scam sleuth who shared some secrets of the trade for a convention audience in Las Vegas.

Deputy state Gaming Control Board chief James Taylor told a full-house conference audience at the Global Gaming Expo on Monday that the most basic scams can be the hardest to stop.

Nevada gambling regulators made more than 600 arrests in 2015, Taylor said, and casino employees make up about 25 percent of arrests every year.

“The sad part is that even management is a large part of our arrests every year,” he said, according to the Las Vegas Review-Journal.

Some schemes are elaborate, like marking cards with an ink visible only to someone wearing special contact lenses, Taylor said.

Others are simple, like pilfering chips and bolting for the door.

Taylor said that in one case, a control board agent counted $220,000 in losses attributed to one man, now 35.

“It’s easy to see but they’re (immediately) out the door,” Taylor said. “So, then we’re backing up the video, getting their pictures, then we have to catch them when they do it again, and there are so many opportunities for them on the Strip.”

Once investigators identify thieves, their names and faces can end up on the board’s Excluded Person List, a published roster of people banned from entering casinos commonly referred to as the “Black Book.” Taylor said that helps agents spread the word about who to look out for.

The chip thief was added to the list last year, becoming one of 48 currently on the list.

Other cheaters target craps, which Taylor said is difficult to police due to activity around the table.

An ex-Las Vegas casino craps dealer and two friends were each sentenced in April to at least four years in state prison and ordered to repay more than $1 million reaped through phantom “hop” bets placed verbally amid last-second activity before the roll of the dice.

Another former craps dealer pleaded guilty to a lesser theft charge and gave a grand jury what a prosecutor called a crucial insider’s account of the scheme