Authorities say a gunman shot dead in a gunbattle after killing a courthouse security guard and wounding a federal marshal in Las Vegas had a "lengthy" criminal history in Tennessee and California.
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 Wicks lost a federal lawsuit 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.
Officials say the wounded marshal has been released from the hospital.
A passerby who was reporting for jury duty caught dramatic cell phone footage of the shooting, which revealed that more than 40 shots were fired.
"We don't believe it's terrorist-related at all," FBI Special Agent Joe Dickey said during a press conference Monday. "It looks like a lone criminal act."
Dickey said the shooter wore black pants, a black shirt and a black jacket. He said the man walked into the building with a shotgun under his jacket and opened fire.
The building was evacuated, police and news helicopters circled overhead, and Las Vegas police cordoned off the area for several blocks. A 16-story state and local courthouse two blocks away was locked down as a precaution.
After police arrived, paramedics wheeled at least two people down a ramp to ambulances.
Witnesses said a man wearing combat boots and fatigues was found dead in the bushes near the courthouse, Fox5Vegas.com reported.
Dickey called the building evacuation "standard procedure" in such an incident, adding it was "for the safety of everybody in the place."
Las Vegas police spokeswoman Barbara Morgan said the shooter had been shot in the head.
"It looks like he went in there and just started unloading," Morgan said.
The Lloyd D. George U.S. Courthouse and Federal Building is named for a longtime senior federal judge who still hears cases. It has federal courts and offices for federal officials including U.S. Sens. Harry Reid and John Ensign. Neither was in the building at the time, authorities said.
Irwin said she saw shotgun casings on the floor of the federal building lobby.
The Associated Press contributed to this report.