Updated at 4:45 p.m. ET: There is a sad update to a pot bust that included a 5-foot alligator-like creature that was allegedly used by his owner to guard drugs in Castro Valley.

Veterinarians at the Oakland Zoo reported Thursday that Mr. Teeth died overnight.

Dr. Karen Emanuelson said the animal, which looks like an alligator, was actually a dwarf caiman. And when he came to the zoo Tuesday after an unusual drug bust, he was critically ill and non-responsive.

Veterinary staff said they examined Mr. Teeth, took blood samples and determined his prognosis was poor. Emanuelson confirmed Thursday that the animal died sometime in the night, but no one at the zoo would explain or discuss any more. It was not clear why the caiman, thought to be about 16 years old, died, or if guarding drugs at a man's house had any connection to his death.

The odd story of the caiman came to light when Alameda County  sheriff's deputies walked into a house earlier this week on the 19000 block of Mount Jasper Drive in Castro Valley to do a routine probation check.

The found the suspect, 32-year-old Assif Mayar, and the drugs and the animal.

Mayar said he acquired the caiman in 1996 to commemorate the death of rapper Tupac Shakur, deputies said.

The caiman was found in a Plexiglas tank in one of the bedrooms and was being used as a deterrent to would-be thieves.

Sgt. J.D. Nelson said when deputies got to the bedroom they found Mr. Teeth "guarding" a 34-pound stash of dried, processed marijuana worth about $100,000."

When NBC Bay Area knocked on the door Wednesday night, the lights at Mayar's home were on and dogs were barking, but no one answered. Neighbors told NBC Bay Area that Mayar and his wife moved into the house about two years ago before their son was born.

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A mother of two who didn’t want to be identified said she’d been inside that house before but noticed and heard nothing out of the ordinary.  "They’re just family people like us, and she has a little boy, very cute, about 20 months, so of course you wouldn’t suspect or expect anything like this from this neighborhood," she said.

Another neighbor, who also did not want to be named, added: "It doesn’t belong in a neighborhood with little kids, and there are lots of little kids. There’s a school about a block away, and if the thing got out, that could be really dangerous."

Caimans are generally from South and Central America and require a lot of care. They need a heat source, a large pond with extra space, and fresh meat bi-weekly.

Mayar was booked into the Santa Rita Jail in Dublin on drug possession and sales charges. It was not immediately clear if additional animal cruelty charges would be considered.

NBC Bay Area's Stephanie Chuang contributed to this report.