CONIFER, Colo. (CBS4)– Two dogs that brutally attacked and killed a woman they knew, were put down one day after the attack. The owner of the dogs, the victim’s son, knew the animals could become aggressive years before the deadly attack.

Susan Shawl was attacked in a doorway to her garage on Monday evening. The dogs mauled her face. Investigators don’t know what caused the dogs to attack.

Susan Shawl (credit: Facebook)

Susan Shawl (credit: Facebook)

“The son heard a commotion and called us. He didn’t initially see what happened,” said Jeffco Sheriff’s Office spokeswoman Dionne Waugh.

Deputies arrived after the frantic 911 call to find the dogs on a deck and a gruesome scene.

Richard Shawl (credit: Facebook)

Richard Shawl (credit: Facebook)

Authorities said that the two pit bulls belonged to Susan Shawl’s son, Richard Shawl, 36. He was also attacked, bitten on the arm while trying to pull the dogs off his mother.

(credit: CBS)

(credit: CBS)

The attack happened in the home that the mother and son shared on Black Widow Drive in Conifer.

Jefferson County Animal Control took the dogs from their home to Foothills Animal Shelter in Golden where they were quarantined under court order. Authorities said that Richard Shawl gave permission for his dogs to be euthanized there, which happened Tuesday evening.

(credit: Facebook)

The dogs that attacked and killed a woman at her home in Conifer (credit: Facebook)

Officials said that Richard had already been issued a warning citation in 2008 after a neighbor reported that the dogs had gotten loose and were behaving aggressively.

The Jeffco Sheriff’s Office told CBS4 that the investigation into the deadly attack was ongoing and it was not clear if Richard would be facing charges.