It took a Taser, multiple deputies and a K9 unit to subdue Harrouff so officers could pull him from 59-year-old John Stevens, from whose face the teen was biting pieces of flesh, according to a post on the Tequesta Police Department's Facebook page.
"K9 Boss allowed the deputies and officers on scene to gain the needed compliance that the Taser was unable to achieve," the post reads.
Snyder called the teen "abnormally strong."
Harrouff fatally stabbed Stevens and his wife, 53-year-old Michelle Mishcon, at their home in a high-end community in Martin County, Florida.
The teen, Snyder said, was coming from dinner with his parents about four miles away. The couple was in their garage, a frequent hang out spot for the husband and wife. Mishcon called it the "garage-mahal," Stevens' son, who bears his name, said.
A neighbor tried to intervene but was stabbed, too, Snyder said. He was taken into surgery Monday night with "substantial trauma," according to the sheriff.