Harold Smith, 43, fatally shot himself last week when police tried to question him about Chasen's murder. Smith was a convicted felon, and his neighbors said he bragged about playing a role in Chasen's death.
Smith, a transient, had a long rap sheet of robbery and drug crimes.
"This was random act of violence," said Beverly Hills police Sgt. Michael Publicker. "With Mr. Smith's background, we believe this was a robbery gone bad."
According to police, Smith's mode of transportation was his bicycle, which was recovered by the Los Angeles Police Department the night he committed suicide.
Authorities said they were tipped off about smith by the TV show "America's Most Wanted."
Police believe Smith acted alone and Chasen's murder was not a professional hit.
Smith openly bragged to acquaintances he was the killer and was waiting to get paid $10,000 for the hit, a theory police dismiss.
At the Harvey Apartments where Smith committed suicide, the opinions over vary widely. Some said Smith was an ex-convict with a violent past. Other said there's no way he rode his bicycle to Beverly Hills and killed Chasen.
"It doesn't add up to me," said Robin Lyle, a neighbor. "I saw this guy every day. He shook my hand, gave me a hug and he was cool."
Songwriter Carol Connors knew Chasen. She said she's still trying to wrap her head around her friend being in the wrong place at the wrong time.
"I have found myself speechless over this," Connors said. "The absurdity of it is mind boggling."
Chasen, a 64-year-old veteran Hollywood publicist, was shot to death Nov. 16 while driving her Mercedes-Benz on the 800 block of North Whittier Drive near Sunset Boulevard in Beverly Hills.
Chasen was driving home about midnight after attending a premiere for the film "Burlesque," which she was promoting.