The mystery behind the murder of top Hollywood publicist Ronni Chasen took a new twist Saturday, when tests on a possible murder weapon reportedly turned up negative.

Police tested the gun that a small-time crook used to kill himself on Wednesday, after the man allegedly bragged to neighbors that he was responsible for Chasen's murder.  

The weapon did not match the bullets fired at Chasen, who was shot in the chest five times while driving her Mercedes in Beverly Hills on Nov. 16, according to KTLA-TV.

The dead ex-con -- identified as Harold Smith, 43 -- was initially considered a suspect because he bragged to neighbors that he was going to be paid $10,000 for carrying out the hit on Chasen.

He also told them that "I would die" before being taken alive.

A viewer of "America's Most Wanted" reported Smith to the show's producers, who told cops.

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