After a month-long search, Barnstable police found and arrested an Onset man Wednesday who was wanted for violating his probation and has since added weapons and narcotics charges stemming from a December traffic stop in Hyannis.

According to the Barnstable Police Department, 21-year-old Timothy Galvin of Onset and his girlfriend, 19-year-old Mercedes Pearson of Plymouth, were charged with trafficking heroin and possession of cocaine with intent to distribute.

Galvin was also charged with carrying a firearm without a license, resisting arrest and a number of other offenses.

Barnstable Street Crime Unit members Yarmouth Officer Nicholas Ambosini and Barnstable Officer Scott Wright were in the area of Route 132 and Bearses Way, Hyannis at 6 p.m. on Dec. 13 when they observed a gray Nissan Altima pull into a Cumberland Farms parking lot.

A young man and woman, later identified by police as as Galvin and Pearson, went into the store and several minutes later only Pearson left and got back into the car. Pearson began to leave the area in the Nissan Altima and a check of the vehicle’s registration plate revealed the registered owner was a woman from Plymouth and had an outstanding arrest warrant.

Officers Ambosini and Wright stopped the car on Bearses Way in Hyannis and discovered Pearson was not the registered owner. Pearson initially gave officers a false name and was placed under arrest for operating without a license and giving a false name to a police officer.

During a follow up investigation at the traffic stop Wright located a load .25 caliber Beretta handgun. The handgun, along with a cell phone, was in the pocket of a black North Face jacket inside the Altima. The jacket did not belong to Pearson, who was booked and bailed on the motor vehicle charges.

The vehicle was towed back to the Barnstable Police Department and after a search warrant was obtained officers found a small black backpack in the car containing approximately 28 grams of heroin, three ounces of marijuana, three grams of cocaine, and a digital scale.

An investigation was conducted relating to the owner of the black jacket and backpack and it was at this time the man who exited the vehicle at Cumberland Farms was identified as Galvin.

SCU members were able to obtain evidence linking Galvin to the jacket, .25 caliber handgun, and the recovered narcotics. Evidence was also obtained indicating Pearson was involved with Galvin selling narcotics.

At the time of the Dec. 13 motor vehicle stop, Galvin was wanted on a Plymouth Superior Court probation violation warrant. Galvin was convicted of distribution of heroin and cocaine in Plymouth Superior Court in May 2013 and was placed on probation until 2016. In November, a warrant was issued for a violation of his probation.

The Barnstable Police Department Narcotics Unit and SCU began an active fugitive search for Galvin. Addresses in the Plymouth area and Hyannis were searched.

On Jan. 15, Glavin was located with Pearson at 57 Spring St., Hyannis. Galvin attempted to flee and was found hiding in the attic. At the time of his arrest he was found in possession of a knife.

Both were arraigned in Barnstable District Court on Jan. 16. Galvin was held on $50,000 cash bail. Pearson was released on personal recognizes for a future court date.