Investigations into the background of the husband-and-wife pair who attacked an office building in San Bernardino, California, last week found that the couple had been radicalized for a while.

In the wake of the attack, which killed 14 people and wounded 21 more, the Associated Press reports that officials are digging in to the backgrounds of 28-year-old Syeed Farook and his wife, 29-year-old Tashfeen Malik.

Authorities say that the couple had taken target practice at gun ranges in the Los Angeles metropolitan area, and that one of those visits occurred just days before the attack.

David Bowdich, chief of the FBI’s Los Angeles office, said on Monday:

“We have learned and believe that both subjects were radicalized and have been for quite some time. The question we’re trying to get at is how did that happen and by whom and where did that happen? And I will tell you right now we don’t know those answers.”

Officials who searched the couple’s home also reported that they found 19 pipes that could be used for bombs, more than previously thought.

A newly-released photo shows the pair as they first set foot together in the U.S., after the Chicago-born Farook brought his wife from Pakistan, where she was born.

The community continues to mourn the victims of the shooting, and held memorial vigils over the weekend.

[Images via AP]