The Allegheny County Medical Examiner's Office said Wednesday that Gilliam died Tuesday night at the LA Fitness gym in Bridgeville while he was playing basketball.
The office said the cause of death has not yet been determined pending an autopsy which is likely to be completed later Wednesday.
After college, the Phoenix Suns drafted Gilliam as the No. 2 overall pick in the first round of the draft. Besides the Suns, Gilliam also played with the then-Charlotte Hornets, Philadelphia 76ers from 1991 to 1993, New Jersey Nets, Milwaukee Bucks and Utah Jazz. He retired in 2000.
Nicknamed "The Hammer," Gilliam was the leading scorer on the 1987 UNLV team coached by Jerry Tarkanian.
In a statement released by UNLV, Tarkanian, who coached basketball there from 1973-1992, called him one of the best players the university ever had.
"In my ratings, I had Larry Johnson No. 1 and Armen No. 2. He was such a great person. Everybody loved him and he loved everybody," Tarkanian said. "He was such a gentle person and such a caring guy. I am all shook up over it. I think the world of him and am just really shocked."
Gilliam's No. 35 UNLV jersey was retired during a halftime ceremony at the Thomas & Mack Center in November 2007. He became the eighth player in the program's history to receive that honor.
He played at UNLV from 1984-87 and was a key member of UNLV's second NCAA Final Four team in 1987. That team finished the season with a 37-2 overall record and was 18-0 in Big West Conference play.
Gilliam coached and played for the Pittsburgh Xplosion in the American Basketball Association in 2005 and 2006.
