TUCSON - Room 411, a king-bed single in a dark and grimy Motel 6 near the railroad tracks on the western edge of Tucson, served as the staging ground for Jared Loughner's series of pre-dawn errands before last Saturday's shooting spree outside a suburban supermarket here.

Loughner checked into the motel at 12:29 a.m. on Jan. 8, police said, before criss-crossing the city buying ammunition, developing pictures and stopping at gas station convenience stores. Loughner, wearing a baseball hat, approached the hotel's check-in window, made of bullet-proof glass, and used a credit card to rent the room, paying $43.71, according to a source with knowledge of the investigation.

The 22-year-old struck the hotel's overnight front-desk clerk as strange. The clerk told authorities he did not appear to be under the influence of drugs but "was just messed up," according to the source, who spoke only under the condition of anonymity because of the sensitive nature of the investigation.

A few hours after checking in, Loughner was seen pacing along the motel's first-floor hallway - long and straight, with blue swirl carpeting and a white popcorn ceiling. The desk attendant asked him what he was doing, but he did not reply. The clerk told investigators about being "scared" and that "he gave off an aura that frightened me," the source said.

Loughner was alone and was not carrying any bags when he checked into the motel, the source said, and it was not immediately known whether he left anything behind in the room.

The FBI obtained video surveillance from the motel showing Loughner checking into the property and interviewed motel employees and other potential witnesses as they piece together his final movements before allegedly opening fire at a civic gathering at a strip mall some five miles away. Authorities say Loughner killed six people and injured 13 others, including Rep. Gabrielle Giffords (D-Ariz.).

After checking into the Motel 6, Loughner went to a nearby Walgreens to retrieve the film he had developed. The photos showed Loughner wearing a red G-string and holding a gun near his buttocks, according to law enforcement sources.

A few minutes later, at 2:34 a.m., Loughner made a purchase at a Chevron store, and later posted a bulletin on his Myspace page titled "Goodbye friends," according to a detailed timeline of events released Friday by the Pima County Sheriff's Department.

Before dawn on Saturday, Loughner approached the Motel 6 front desk attendant to check out. The clerk told him he had the room until check-out time at noon, but he left anyway, the source said. The clerk told investigators: "Nothing was right with him."

This clerk's reaction to Loughner is significant, the source said, because the hotel regularly attracts some abnormal guests. Several days prior to Loughner's visit, a guest used the bed to barricade himself in his room - Room 415, a few doors down from Loughner's room - and committed suicide by shooting himself in his head, according to the source.

Soon after Loughner checked out of the Motel 6, he tried to buy ammunition at a Wal-Mart store nearby. After those efforts failed, he drove two miles to a Super Wal-Mart store and bought the ammunition.

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