Police have made an arrest in the December murder of Freeport resident Michael Muniz.

Marvin DelaRosa, 20, was arrested Saturday for shooting and killing his 19-year-old friend. DelaRosa claims his innocence, but police say they?ve discovered DelaRosa?s motive.

Nassau County police say DelaRosa planned to rip Muniz off because he knew Muniz sold marijuana from his car. Cops say that on Dec. 5, DelaRosa called Muniz from a pay phone to prevent the call being traced. They say DelaRosa arranged to meet Muniz on Harris Avenue in Freeport and then shot his friend in the chest.

?Michael didn?t want his family to know what he was doing,? Detective Sgt. Dennis Barry says. ?It was a well-known fact that he kept his stash in the car.?

Barry says Muniz got out of the car in an effort to get away, but dropped in the street. Police say DelaRosa then drove off in Muniz?s car, parked it at a location further away in Freeport, took whatever drugs he could find and fled. They believe DelaRosa dumped the murder weapon in a canal in Freeport.

DelaRosa denies the allegations, and says he was at a friend?s house all day when Muniz was shot.

DelaRosa was arraigned Sunday in Hempstead. Members of Muniz?s family who were there were too upset to talk. However, one family member says that they are happy an arrest has finally been made.

Police call the case one of bad blood, saying crime runs in the DelaRosa family. DelaRosa?s brother, Omar, was convicted of murdering Anthony Battaglia in 2003 as Battaglia was walking home from the train station.

DelaRosa is being held without bail.