FBI Special Agent in Charge Kevin Favreau said Tuesday that 66-year-old Johnny Lee Wicks faced murder charges in Memphis, Tennessee, in the mid-1970s, and sex assault charges in Sacramento, California, in the late 1980s.
Records show last year challenging a cut in his Social Security benefits after moving from California to Las Vegas.
The FBI and local police say Wicks torched his apartment and walked 3 miles to the courthouse before opening fire Monday morning, killing 72-year-old security officer Stanley Cooper.
A neighbor, Johnetta Watkins, said she didn't see Wicks after firefighters doused the fire.
Watkins, 56, used to drive Wicks to the grocery store. She described him as a quiet man who walked with a limp, lived alone and sometimes complained that Las Vegas was a "prejudiced" place to live. He also complained about what he called an unfair cut in his Social Security benefits, she said.
"He hated living in Las Vegas and he had spoken about moving back to California," Watkins said, recalling that Wicks moved in about mid-2007. "He said that he had had several strokes ... and that he was distraught because the government was taking most of his money. They had cut his funds and he was very upset about that."
In a handwritten lawsuit filed in March 2008, Wicks complained that his Social Security benefits were cut following his move to Las Vegas, and he accused federal workers of discrimination because of his race.
"Lots of state worker(s) and agencies have took part in this scam mainly for old blacks who are not well educated," Wicks wrote in the seven-page complaint.
Wicks claimed the problem began in California, after he had a stroke and was unable to go to government offices to protest an earlier benefits reduction. He alleged Social Security staff called his new landlord in Las Vegas and told her not to help him.
The case was dismissed Sept. 9 by U.S. District Court Judge Philip Pro in Las Vegas following a hearing before federal Magistrate Judge George Foley Jr. Both judges have courtrooms in the federal building.