A 30-year-old man was convicted Wednesday in Baton Rouge federal court on a charge that he was a felon in illegal possession of a firearm in May 2009 when two police officers stopped him for a traffic violation.

Lonnie Poydras, 30, of Baton Rouge, became a convicted felon in 2001 when he admitted in a 19th Judicial District Court case that he was part of a three-man crime spree that included the shooting death of Demetrius White at a canal bridge on a service road of Florida Boulevard.

“The conviction in this case demonstrates our commitment to prosecuting felons who possess firearms,” U.S. Attorney Donald J. Cazayoux Jr. said after the verdict by a jury of seven women and five men.

Cazayoux and East Baton Rouge Parish District Attorney Hillar C. Moore III said last month that they are pushing hard for cases that send convicted violent offenders back to prison for illegal possession of firearms.

More than a decade ago, Poydras was sentenced to 10 years in state prison for his guilty plea to a charge of conspiracy to commit armed robbery. A co-defendant was convicted of the second-degree murder of White in that 2001 case.

Poydras admitted in that state court case that he and his co-defendants also had robbed a grocery store, taken a deputy sheriff’s pistol and cellphone at gunpoint, stolen an LSU student’s 1991 Oldsmobile Royale and carjacked a 1996 Chevrolet Cavalier from three other men.

Poydras later was convicted at trial in 2010 of illegal possession of a .40-caliber pistol discovered by two Baton Rouge police officers after they stopped him on North Harrell’s Ferry Road for driving his Chevrolet Tahoe without a license plate. The pistol was between the driver’s seat and the Tahoe’s console.

In 2011, Chief U.S. District Judge Ralph E. Tyson sentenced Poydras to six years in federal prison for that jury conviction. But Poydras persuaded the 5th U.S. Circuit Court of Appeals to overturn the conviction, arguing that jurors should not have heard some witness testimony about his character.

After Tyson’s death in July 2011, Chief U.S. District Judge Brian A. Jackson merged Poydras’ case onto his court schedule.

This week, Assistant U.S. Attorney Michael J. Jefferson asked jurors for “an appropriate verdict, a just verdict … guilty as charged.”

Defense attorney Michael A. Fiser argued, “This case is not nearly as clear-cut as Mr. Jefferson would have you believe.”

Jurors, however, sided with Jefferson.

Jackson scheduled Poydras’ sentencing for July 12.