[UPDATED Thursday, March 7, 11:47 a.m.]

Police arrested a Charlestown man after an investigation led them to investigate a possible drug sale at the McDonald's on Montvale Avenue on Monday.

According to a release, on Monday, March 4, members of the Woburn Police Department Drug Unit arrested a man on charges related to drug distribution.

The Southern Middlesex Regional Drug Task Force and Woburn Police Department patrol officers also assisted in the investigation.

Police arrested Shane Michael Smith, 21, of 31 Tibbetts Town Way, Charlestown. Shane was charged with one count of Distribute a Class B Drug (Oxycodone/Percocet) and one count of Possess to Distribute Class B Drug (Oxycodone/Percocet). 

According to the release Smith was known to Woburn Police to have been conducting the sale of Oxycodone/Percocet in the Woburn area. As part of the investigation police initiated an undercover drug purchase on Smith on Jan. 24.

On March 4 police received information about a possible drug sale at the Montvale Avenue McDonald's. Police set up surveillance and positioned officers in and around the restaurant.

After police identified Smith, who was in a vehicle with three other males, they approached the car and made an arrest. After a search of the vehicle and its occupants they recovered 32 Oxycodone/Percocet tablets. Police also found 1.3 grams of marijuana and an Elite-II replica Beretta BB-gun in the possession of a second male and a M-Tech USA double edged folding knife in the pocket of a third male in the vehicle.