Federal investigators are searching a New Bedford landfill for evidence connected to the marathon bombings. 

Update 9:46 am - FBI and State Police have been combing through mounds of trash at New Bedford's Crapo Hill Landfill in search of items dumped there from a New Bedford apartment dumpster.

A source says investigators are looking for a black trash bag with a backpack inside believed to belong to marathon bomb suspect Dzohkar Tsarnaev. Since Monday, officials have brought in dogs and a hazmat crew to help in the search.

The trash comes from the apartment complex where 3 people were arrested Friday, believed to have ties with Tsarnaev. The area has been taped off with crime scene tape and guarded by a police officer.

It's near the dorm room of Dzhokhar Tsarnaev at UMass Dartmouth, where he was reportedly seen after the incident.  They're looking for sales receipts, packaging or anything that might have been used in test explosions.

Last Friday night Dzhokhar Tsarnaev was taken into custody after a day long manhunt in Watertown, MA. That manhunt saw the other bombing suspect, Tamerlan Tsarnaev, killed in a shootout with police.

The two Tsarnaev brothers used pressure cooker bombs in the attack. They used two at the marathon, and then another during the encounter with police in Watertown. Other than the pressure cooker bombs, the men were believed to have homemade grenades.