Officials investigate how guns bought by neighbor ended up with San Bernardino terrorists

RIVERSIDE, Calif. (KABC) -- The family of Enrique Marquez, the man suspected of buying high powered rifles the San Bernardino terrorists used in their Wednesday attack, refused to answer questions from the media on Monday.

Marquez's family left their Riverside home and returned an hour later after shopping for what appeared to cleaning supplies, including a new vacuum.

MORE: What we know about San Bernardino attack

Damage from a Saturday morning raid by the FBI was still apparent from a broken window to a gaping hole in the garage.

FBI officials returned to the home Sunday to collect more evidence.

ABC News learned investigators with the FBI questioned the 24-year-old man.

Investigators said Marquez lived next-door to Syed Farook for years in Riverside.

Neighbors said Marquez and Farook shared a common interest in cars.

But it appears they also shared an interest in guns, as investigators said Marquez legally purchased the two rifles in 2011 and 2012.

Farook also purchased two hand guns during the same time frame.

Officials are trying to determine how the rifles ended up with Farook and his wife Tashfeen Malik.

MORE: The 14 victims killed in San Bernardino terrorist attack

"Right now, our major concern the FBI, ATF and JTTF and is determining how those firearms and the rifles in particular got from Marquez to Farook and Malik," John D'Angelo, Assistant Special Agent in Charge with the ATF said.

The FBI has not named Marquez as a suspect and his whereabouts are unknown since he checked himself into a mental health care facility on Friday, according to ABC News.

CORRECTION: An earlier version of this story reported that Enrique Marquez is 29 years old. It has since been corrected to say he is 24 years old.