The gunman who helped turn a San Bernardino holiday bash into a slaughterhouse had been made fun of by his co-workers for his beard, his family's lawyers claimed Friday.

Syed Rizwan Farook was a devout Muslim who wore a beard for religious reasons and "usually shrugged off any jokes that were made about this facial hair," attorney David Chesley said.

"He was a very isolated, introverted individual, with really no friends that we could identify" in the San Bernardino County Health Department, where he had worked for five years, the lawyers said.

Chesley and attorney Mohammad Aubershaid made the comments during a news conference aimed at slowing what they argued was a rush to judgment by the FBI and media to declare Farook and wife Tashfeen Malik terrorists.

Syed Farook appears in a ID photo from California State University California State University, Fullerton

The lawyers, who represent Farook's mother, two sisters, and brother, spoke shortly after the FBI announced that the agency was investigating the mass shooting as an act of terrorism.

Chesley said the family was "totally shocked" after learning that Farook and Malik had gunned-down 14 people and wounded 21 more Wednesday at the city's Inland Regional Center. The couple was later killed in a shootout with cops.

Related: How Did Tashfeen Malik Go From Housewife to Killer?

Pakistani-born Malik pledged allegiance to the leader of ISIS on Facebook just before she and her husband carried out the massacre, law enforcement sources told NBC News.

The Farook family lawyers insisted, however, that they haven't seen any evidence to warrant a terrorism investigation and said the couples' kin had no idea they had supposedly become "radicalized."