A young man now on trial for killing a restaurant owner in 2003 first came to authorities’ attention months before when he tried to buy $8,000 worth of electronics with a stolen credit card at an Atlanta-area Best Buy store.

It was the first clue, prosecutors say, of Rejon Taylor’s elaborate identity theft-and-robbery scheme in Atlanta’s Buckhead neighborhood. That scheme turned into the stalking, interstate kidnapping and murder of one of his wealthy victims on Aug. 6, 2003, alongside a road in Collegedale, Tenn., prosecutors said.

Prosecutors say Mr. Taylor shot Buckhead restaurant owner Guy Luck through the mouth when he found out the restaurant owner might have figured out who had broken into his Buckhead house at least five times.

If convicted, Mr. Taylor, 24, could be sentenced to death.

Testifying on the third day of Mr. Taylor’s federal murder trial in Chattanooga, law enforcement officials say that, a few months before the killing, a checkbook belonging to Mr. Luck was found in a suburban Atlanta apartment that Mr. Taylor had abandoned.

Lt. Matt Wolfe of the Rockdale County (Ga.) Sheriff’s Office testified Friday that a warrant for Mr. Taylor’s arrest was issued in the spring of 2003 after the checkbook and countless pieces of stolen mail, several stolen credit cards and other documents tied to the suspect were found in the apartment in Conyers, Ga.

In other testimony Friday, former detective Margaret Clouden, who worked for the DeKalb County, Ga., Police Department, said she questioned Mr. Taylor in January 2003 after the incident at the Best Buy, which was located in DeKalb.

“He told me he got the credit card from a drug dealer,” Ms. Clouden said. “I knew it was a lie.”

Prosecutors say Mr. Taylor had a “reckless disregard for life” when he led the charge to kidnap Mr. Luck from his home, drive north on Interstate 75 and eventually shoot him in Collegedale.

He is the only person tied to the crime who has not pleaded guilty. His two friends, Joey Marshall and Sir Jack Matthews, pleaded guilty to murder, carjacking and kidnapping and now face mandatory life sentences without the possibility of parole.

“I have never seen a case with this much evidence against someone where they have not pleaded guilty,” Lt. Wolfe said Friday.

Mr. Taylor’s trial is expected to last six weeks and involve at least 25 witnesses.