CENTENNIAL, Colo. -- The man who prompted a federal investigation into a possible Barack Obama assassination plot was set to be formally charged on state drug and weapons offenses Thursday morning but his case was transferred to federal jurisdiction.

Tharin Gartrell, 28, was in Arapahoe County Court on a return of advisement.

"This case is no longer with the DA's office," said Arapahoe County District spokeswoman Kathleen Walsh. "The case is now being filed in federal court."

Gartrell was spotted driving erratically near Parker and Hampden in Aurora around 1:30 a.m. Sunday.

Authorities said police found scoped rifles, wigs, fake IDs and a bulletproof vest in the 28-year-old's rented truck. The resulting investigation led to the arrest of Gartrell along with Nathan Johnson, 32, and Shawn Adolf, 33 -- men who authorities said talked about killing Obama.

The U.S. Attorney's Office later said Gartrell and the other men had no firm assassination plot and were making racist threats. That investigation was continuing.

A spokesman for the U.S. attorney could not say why Gartrell was on crutches when he made his federal appearance Thursday afternoon. Aurora police said he was using crutches when he was arrested.

Gartrell was handcuffed to the crutches and spoke little in court Thursday, answering the judge with "Yes, your honor" and "No, your honor." He did not enter a plea.

Public defender Ed Harris was appointed to represent him. Harris was not present and did not immediately respond to a telephone message.

Arapahoe County prosecutors had planned to charge Gartrell Thursday with state drug and weapons violations, but that was put on hold without explanation.

U.S. attorney's spokesman Jeff Dorschner said it was "best from a coordination standpoint" if the cases against Gartrell and the two other men were in federal court.

State prosecutors sometimes defer to their federal counterparts if a suspect can get a stiffer sentence in federal court.

Adolf also faces federal charges of possession of a firearm by a convicted felon, possession of body armor by a violent felon, and possession of a controlled substance. Adolf is in state custody in Burlington, Colo.

Johnson is charged with possession of a firearm by a convicted felon, and possession of methamphetamine. He is in state custody in Denver.