BOSTON -- A former Boston police detective who says that former FBI agent John Connolly ruined his career has asked a federal judge to sentence Connolly to the maximum for racketeering.

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NewsCenter 5's David Boeri reported that Frank Dewan said that Connolly disrupted the Boston Police Department's investigations into James "Whitey" Bulger and Stephen "The Rifleman" Flemmi because the two were informants for Connolly.

"We were getting close on the drugs and trafficking and that was one thing they couldn't stand, to have Bulger and Flemmi tainted by drugs," Dewan said. "So they decided to come after me."

In the 1980s, Dewan was a sergeant detective investigating Bulger, while Connolly was Bulger's FBI handler. Among the crimes Connolly has been convicted of is writing an anonymous letter on Boston police stationary to a federal judge falsely accusing Dewan of tarnishing his badge.

"John Connolly effectively ruined my career with the letters he wrote about me," Dewan said.

Dewan wrote to U.S. District Judge Joseph L. Tauro that Connolly used similar tactics to undermine other law enforcement efforts.

"John Connolly operated in an anonymous and cowardly way be repeatedly alleging unlawful activity on the part of other law enforcement agencies and or officers in order to protect himself and The Bulger Group," Dewan wrote.

In 1990, thanks to Dewan and his team, the first real links were established between Bulger and drug trafficking in South Boston. Connolly's links to Bulger were suggested as well. In a raid of the Bulger-owned South Boston Liquor Mart, investigators found a liquor sales slip from Dec. 13, 1989. Written on the back was the name of FBI agent Dick Baker, and the note "friend of John Connolly."

Dewan wrote that the liquor was sold on the date of the FBI Christmas party and was going to be given away as door prizes.

"He just said that the Boston police planted the evidence," Dewan said.

Dewan denied ever planting anything.

Because of the humiliation, embarrassment and falsehoods, Dewan said he ended his police career under a cloud.

Dewan wrote to Tauro that Connolly should go to prison immediately, because he said Connolly poses a risk of flight.

Sentencing guidelines call for a range of just over eight years to just over 10 years in prison.