He checked into a down-and-out motel. He picked up photos showing him holding a Glock 19 while wearing only a bright red G-string. He bought ammunition on one of three trips to two different Walmarts.

He called a high-school pot-smoking buddy, ran away from his father into a cactus-dotted desert and updated his MySpace profile to say, “Goodbye friends.”

Michelle Martinez ran into Loughner during his rambling odyssey. She and some friends were hanging out in the neighborhood when a sullen figure emerged from the darkness in a black hooded sweatshirt and startled them. Loughner picked his way through the group rather than walk around them, offering a deep, distant “What’s up?” He then quickened his pace and disappeared into the darkness.

“I had a feeling he was thinking about something,” said Martinez, who knew Loughner from their school days. “It was just kind of weird.”

The encounter epitomizes Loughner’s final hours as he became increasingly unhinged, culminating with him opening fire on a crowd of people at an event for Rep. Gabrielle Giffords. Six people were killed and 13 were wounded amid a barrage of bullets from a Glock 19.

Authorities do not know what pushed the 22-year-old mentally disturbed loner over the edge, but interviews, records and a police chronology released Friday provide a fuller picture of his movements that in many ways reflect his scattered mind.

It would all play out within a few miles from the modest, single-story home where he grew up and lived all his life — save for a brief attempt he made at living in an apartment by himself.

The chaotic night, according to the official law enforcement chronology, began at 11:35 p.m. when he dropped off a roll of 35 mm film at a Walgreens.

In the next hour he stopped at a Circle K gas station/convenience store and checked into a Motel 6, a $37.99-a-night spot popular with truckers near a Long John Silver’s and other fast-food restaurants.

If he slept at all that night, it wasn’t for long.

At 1:45 a.m., he was back outside his parents’ home, where he ran into Martinez and her friends.

At about 2 a.m., Loughner called an old friend, Bryce Tierney. They had been confidants in high school but hadn’t talked for months — another in a series of friends with whom Loughner severed ties amid his increasingly bizarre behavior.

Loughner used to bang the drums in Tierney’s garage while his friend jammed on the guitar. They used to talk philosophy, about how the modern world was draining people of individualism. They got high, as police found out when they pulled the two over in September 2007 and Tierney admitted they smoked a joint in a van on the way back from a convenience store.

Early Saturday, Tierney was up watching a real-life ghost chasers show on TV. When his cell phone rang, the incoming number was listed as blocked, so he didn’t answer.

Tierney picked up the message immediately. It had a melancholy tinge: “Hey Bryce, it’s Jared. We had some good times together. Peace out.”

After the call, Loughner headed back to the Walgreens, where — at 2:19 a.m. — he picked up the developed photos. And 15 minutes later, he stopped to make more purchases at yet another convenience store.

At 4:12 a.m. Loughner was at a computer keyboard in an unknown location, typing a farewell bulletin on his MySpace page — “Goodbye friends.” Authorities said the photo included in that posting was from the shots developed at Walgreens hours earlier.

After one additional stop, at another Circle K, Loughner began his quest for ammo. His first stop, a Walmart between his house and the scene of the shooting, doesn’t sell bullets before 7 a.m. It was only 6:12 a.m. He returned at 7:04 a.m., but left the store without making a purchase.

He then drove 5 miles west to a Walmart superstore, where he purchased 9 mm ammunition and a black, backpack style diaper bag. It was now 7:27 a.m.

Just three minutes later, he was pulled over for running a red light in his 1969 dark gray Chevy Nova.

Loughner was cooperative, and the officer from the Arizona Game and Fish Department took his driver’s license and vehicle registration information. Loughner had no outstanding warrants and was let go with a warning. And without a search.

The only thing the officer saw in the car was fast-food wrappers.

Around 8 a.m., Loughner had returned home. And there was his father, Randy, who had questions for his son.

The confrontation happened in the driveway.

The son pulled a black bag from the trunk of the Nova; Randy Loughner demanded to know what was going on.

“The father went out and said, ‘What’s that?’ and he mumbled something and took off,” Sheriff Clarence Dupnik said.

Loughner was desperate to escape. He hustled toward the corner where he used to catch the school bus with his neighbor Martinez, then hung a right and a quick left before entering a sandy wash that runs behind the houses on the other side of his street, North Soledad Avenue.

Winding his way through the desert scrub and cactus, Loughner arrived at a dry tributary 300 feet later that dead-ends into a bigger wash. His father jumped into his truck to catch up with his son.

But his son had disappeared from view.

Jared Loughner was alone again.

The only clue about the desert pursuit that has turned up is the black bag recovered Thursday at the intersection of the two washes. Inside, they found the same caliber of ammunition Loughner bought at Walmart.

Loughner’s escape route took him up the wash, past the back of a post office, to where the dry stream bed opens into a broader swath of desert. In this part of suburbia, brush-choked expanses are never far away.

Eventually, Loughner returned to the Circle K he’d visited three hours earlier.

He was carrying two extended pistol clips that hold up to 31 bullets, along with two 15-round magazines, a four-inch buck knife, a Visa card, his driver’s license and cash in a plastic bag.

Authorities said a cab picked him up at 9:41 a.m.

His destination was a Safeway store — and a violent confrontation with Gabrielle Giffords.

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Associated Press Writer Jacques Billeaud in Phoenix and Pete Yost in Washington contributed to this report.