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THORNTON, Colo. — Thornton Animal Control officers are investigating whether a “two-year-old blue American Pit Bull terrier type dog” was provoked when it attacked and killed a Chihuahua visiting the house next door.

The two dogs were in front of a pair of homes in Thornton on Aug. 17, when the scuffle occurred.

“That’s all I think about – just watching helplessly. There was no control over the animal. There was nothing anybody could do to stop him from killing our dog,” said Donna Tafoya, the Chihuahua’s owner.

Tafoya said the Chihuahua was a gift from her son nine years ago, before he passed away.

“Our house is extremely quiet. There is a huge part missing in our lives now that he is gone,” said Tafoya.

FOX31 reached out to the owner of the larger dog but did not hear back by our deadline.

According to Thornton police, Animal Control officers responded to 128 reports of aggressive animals during the past year.

Of those, 26 resulted in a summons because officers determined an animal aggressively attacked another animal or a human. A judge then helps determine the fate of the animal in those cases.

A handful of cases are still open, according to Thornton police, including the case involving the Chihuahua.

Officers are still interviewing witnesses in that case. They are investigating whether the animals were wearing leashes and which property they were on during the attack. They are also trying to determine whether the larger dog was provoked.

Lori Jane Gliha wrote this report.