A Richmond police sergeant took $140,000 in bribes from drug dealers and set up a narcotics deal for another, while alerting that dealer of a federal drug agency's tracking device on his car, according to a Contra Costa District Attorney witness.

Sgt. Michael Wang also tipped off a drug dealer to a gun sting that led to the shooting of a police informant, according to that witness.

The allegations against Wang -- a Richmond police personnel and training supervisor, and former narcotics officer -- came from Sergio Vega-Robles, a prosecution witness in a related drug conspiracy trial. Last month, Vega-Robles was interviewed by an inspector from the district attorney's office, and his allegations against the 18-year veteran of the force were made public this week in a motion filed by an attorney representing an accused drug co-conspirator.

"If these allegations are true, then (Wang's) a gangster of the worst kind," said Daniel Horowitz, an attorney representing co-conspirator Coby Phillips of San Pablo. "He's putting other law enforcement in danger, and he's putting the people helping law enforcement in danger, too."

Wang was placed on paid administrative leave recently while local and federal investigations continue, Richmond police Chief Chris Magnus said.

In a statement Thursday, Magnus said he is aware of a "number of serious and potentially criminal allegations" regarding Wang, which could come up in testimony during Phillips' upcoming trial.

Magnus said he and other Richmond police personnel have been working with local and federal criminal authorities "to ensure the allegations are appropriately addressed."

A call and email to Wang were not returned Thursday, but his attorney Harry Stern called Wang a "highly respected supervisor in the Richmond Police Department."

"There's no question in my mind these allegations are a rather nasty smoke screen planted by the defense to provide cover and distraction," Stern said. "Another defendant was convicted in short order on this, and they saw the writing on the wall, and that's the motivation for dragging Sgt. Wang into this."

Prosecutor Tom Kensok, handling drug conspiracy cases involving Phillips, Sergio Vega-Robles and his brother Jose and numerous other defendants, declined to comment on Sergio's interview, citing the ongoing case.

Sergio Vega-Robles took a deal to testify for the prosecution against Phillips. He had faced charges similar to those of his brother Jose, who was sentenced last year to 75 years to life in prison for operating a major Bay Area methamphetamine ring and the 2004 murders of two drug associates in West Contra Costa County. But the murder charges against Sergio were dropped upon his cooperation with prosecutors, Horowitz said.

Earlier this week, Sergio Vega-Robles' allegations against Wang -- most stemming from around 2005 -- became public in a nearly 200-page motion aimed at dismissing Phillips' attempted murder charge.

In his interview with the prosecution, Vega-Robles said he personally gave Wang two installments of $40,000 each, and a drug dealer associate gave the sergeant another $40,000 on his behalf, Horowitz said.

"He talks about Officer Wang providing information to him which was of value in continuing his narcotics operation. He talks about Officer Wang introducing him to another drug dealer and actually setting up a drug deal (the sale of ephedrine or pseudoephedrine)," the motion claims.

The U.S. Drug Enforcement Agency was investigating Sergio Vega-Robles and his brother Jose. At one point, Sergio Vega-Robles told prosecutors Wang alerted him of a tracking device on his car; Vega-Robles then removed it.

On Feb. 21, 2005, Jose Hernandez -- an alleged Richmond police informant -- was shot three times in the 1800 block of Roosevelt in Richmond. He survived.

Sergio Vega-Robles claimed that before the shooting, his brother Jose was tipped off by Wang about an undercover gun sting in which Jose Hernandez would try to sell him a gun. Sergio Vega-Robles told prosecutors that Wang fingered Hernandez as a police informant and told Jose Vega-Robles he could be arrested if he completes the gun deal.

It was like "he set up Hernandez to get shot," Horowitz said.

In Phillips' 2008 grand jury testimony, Contra Costa district attorney inspector Shawn Pate testified about the implications of outing a law enforcement informant.

"If somebody is labeled as an informant in West Contra Costa County, they suffer grave consequences," he testified.

Most Richmond police evidence regarding the attempted murder of the informant has disappeared, court records show. Horowitz said he plans to subpoena Richmond officers concerning the missing evidence.

If the allegations against Wang are found to be true, he could be criminally liable for the same charges as the other drug co-conspirators, Horowitz said. He and Magnus stressed no other Richmond police officers have been implicated in these allegations; Magnus, citing the ongoing investigation, would not provide more details.

Staff writer Robert Rogers contributed to this report. Contact Matthias Gafni at 925-952-5026. Follow him at Twitter.com/mgafni.