The Michigan Uber driver charged with murdering six people switched vehicles after sideswiping a car at the start of the shooting spree, authorities said on Tuesday, adding that they hoped his phone would help establish a motive for the killings.
It also was revealed that the driver, Jason Dalton, visited a gun shop shortly before the rampage and bought a heavy duty jacket that could conceal a small pistol.
SEE MORE: Michigan Uber driver admits to deadly shooting spree-media reports
Dalton, 45, was denied bail on Monday after a court hearing in which a detective testified that he admitted to the five-hour shooting rampage over the weekend in Kalamazoo, Michigan, about 150 miles (240 km) west of Detroit.
Less than three hours before the first shooting occurred on Saturday evening, Dalton and a friend visited Southwick's, a gun shop he frequented in nearby Plainwell, a shop employee told Reuters.
While Dalton is a regular customer who usually spends time chatting with the staff, he bought the jacket and left the crowded store within about 10 minutes, said the employee, who asked not to be identified.
"He's in here enough for me to know he talks to the guys about guns and different stuff," she said.
Learn more about the story:
Searching for a motive for the violence, investigators are now focusing on a gun and a cell phone seized from Dalton and reports that he drove fares for the Uber car-hailing service in between the shooting episodes, said Paul Matyas of the Kalamazoo County Sheriff's Department.
Prosecutors say Dalton randomly shot at people at an apartment complex, a car dealership and a Cracker Barrel restaurant, killing six and wounding two.
"Right after the first shooting at the apartments, he left the scene and sideswiped a car," Matyas said. The accident prompted him to switch cars, moving from a silver Chevrolet Equinox to a darker colored Chevy HHR, both vehicles belonging to his family, Matyas said.
One of the Uber customers he picked up just before the shootings started told WWMT-TV that Dalton got a call on his cell phone and subsequently "he started driving erratically, running stop signs."
READ MORE: Michigan Uber driver admits to deadly shooting spree
Matyas said investigators were focusing on Dalton's contacts with Uber and working to "track his phone calls, track his whereabouts" in the hours before his arrest early on Sunday.
Dalton had no prior criminal record, authorities said.
"We are no closer to a motive two days later than 10 minutes after he was arrested," Matyas said.
The two surviving victims include a 14-year-old girl, Abigail Kopf, who is in critical condition and Tiana Carruthers, 25, who was seriously wounded but is expected to recover.
More on AOL.com:
Dynel Lane, accused of cutting baby from womb, found guilty of attempted murder
McConnell: Senate won't confirm any Obama Supreme Court nominee
Obama makes final attempt to persuade Congress to close Guantanamo