A dog owner who stabbed and killed a pit bull that was attacking his Doberman pinscher at a dog park last month will not be charged.

Investigators determined that Jeffrey David Black, owner of Spike, the Doberman pinscher, was justified in stabbing Mac, a pit bull owned by Benjamin Johnson, on July 30, after Mac had attacked his dog twice.

Witnesses told police that Mac also had harassed other dogs in Broomfield Commons Dog Park.

After the first encounter on July 30, Johnson claimed his dog suffered some minor injuries, although police later found no bite wounds on the dog.

During the second incident, Mac reportedly bit Spike on the throat and refused to let go, despite attempts by both dog owners and a bystander to separate them. Black then took out a pocketknife and stabbed Mac in the back several times before slitting the dog's throat.

"There is insufficient evidence to prove beyond a reasonable doubt that the killing of Mac was 'needless,' " wrote Adams County District Attorney Don Quick in a letter to Broomfield Police Chief Thomas C. Deland.

"(Black), who was faced with two unfortunate options, was justified, according to the law, in his decision to take the life of Mac in order to save the life of his dog and avoid serious injuries to himself and others."