San Marino Mayor Dennis Kneier was in the dog house Monday after he was caught on video leaving a bag of poop on a neighbor’s property.

The mayor said he and his wife, Liz Kneier, were walking home Saturday from Lacy Park on the 1400 block of Charlton Road when they found the bag of poop near the sidewalk.

In the video footage, caught by neighbor Philip Lao’s home surveillance camera, Kneier and his wife are seen walking several feet before she points at Lao’s walkway and Kneier tosses the bag onto it. The video does not show where Kneier picked up the bag.

“I made a mistake of putting it in his walkway,” Kneier said. “Rather than leaving it, I should have walked on by or disposed of it properly.”

Kneier said he and Lao have not spoken of the incident.

Lao turned the video over to the San Marino Police Department

Officers responded to Lao’s residence around 6 p.m. Saturday and were told that Lao’s wife found the plastic bag containing dog feces on a private walkway leading into their residence, San Marino Police officials said in a press release.

“The bag was tied closed and appeared to have been intentionally placed on the walkway entrance,” officials said. “After reviewing video surveillance which monitors the exterior of their residence, the residents were able to identify their neighbor, Dennis Kneier, as the person who had placed the plastic bag on their walkway.”

Police obtained a copy of the video and took photographs of the plastic bag, officials said.

“It’s still open for investigation,” San Marino Police Chief Tim Harrigan said. Although Lao is a frequent critic of the City Council, police have no reports of previous issues between the two men.

Kneier said he delivered an apology letter to Lao stating, “Dear Phil, Late in the day this past Saturday, June 7, Liz and I were returning from a walk in Lacy Park when we noticed a bag of dog waste in your west parkway near the lamp post. Rather than leave it or dispose of it properly, I placed it on your side walkway. This was a mistake, for which I apologize. It won’t happen again. Sincerely, Dennis Kneier.”