A drug dealer and career criminal who testified against rogue Philadelphia cop Malik Snell at his three trials got his reward yesterday.

U.S. District Judge Jan DuBois sentenced Keith Robinson to six years behind bars after prosecutors filed a motion for leniency based on his cooperation in the Snell case.

Robinson, 32, had been facing more than 21 years in federal prison under advisory-sentencing guidelines, in part because he had state convictions for drug offenses in 1997 and 2005.

Assistant U.S. Attorney Leo Tsao left it up to DuBois to determine how much leniency Robinson should be accorded but said a "serious sentence" was warranted to show Robinson that his crimes had "serious consequences."

Robinson apologized before sentencing, said he "realized [he] hurt [his] community and [his] family," and he asked DuBois for leniency.

DuBois told Robinson that selling drugs is "not a victimless crime," adding, "I cannot undercut the seriousness of your offense by giving you a slap on the wrist."

Robinson pleaded guilty last September to possession with the intent to distribute, after he was found with 37 grams of crack. He has been in federal custody since then.

Robinson agreed to cooperate with prosecutors as part of his plea deal, which included testifying against Snell.

After the first two trials ended in hung juries, Snell was found guilty at his third trial in June of robbing a South Philadelphia drug dealer and of conspiracy, attempted robbery and a weapons offense in connection with a botched home invasion in Pottstown in December 2007. Snell faces a prison sentence of more than 17 years when he is sentenced in September.

Robinson's name came up in connection with the Pottstown case.

In early 2008, he told authorities who were investigating the botched robbery at the Pottstown apartment that he had been selling crack in Pottstown since 2002, court papers said.

He said further that he frequently kept the proceeds of his drug sales for safekeeping with a friend, Sharon Minnick, who lived at the Pottstown apartment that Snell and two others tried to rob.

Prosecutors said Snell and his two accomplices were told they would find some of Robinson's drug proceeds at the apartment, court papers said.

Minnick testified on behalf of Robinson yesterday, telling the court that he was "like [her] son" and had "inspired" her to overcome alcohol and drug addiction.