The mayor of San Marino was caught on surveillance video tossing a small bag of dog poop into a neighbor's frontyard, and the homeowner is refusing to accept his apology.

Resident Philip Lao said he discovered the small bag outside his home Saturday evening before going on a walk with his wife.

After returning, he viewed footage from his home surveillance cameras to find out who dumped the bag near his frontyard. To his surprise, Lao recognized the culprit as Dennis Kneier, mayor of the wealthy San Gabriel Valley community.

“We have not been able to sleep at night for a while because of this,” Lao said.

Kneier appears in the surveillance video holding a briefcase in his left hand and a small bag in his right as he walks in the 1400 block of Charlton Road.

A woman, who was later identified as Kneier’s wife, Liz, was walking a few steps ahead of him and appears to say something to him, then points toward Lao’s walkway moments before he tosses the bag.

Lao called police about the incident and officers took a report, indicating the bag “appeared to have been intentionally placed in the walkway entrance,” the San Marino Police Department said in a statement.

Although police said Lao does not want to press charges, detectives are still investigating the incident.

Lao claims the mayor has not been “happy” with him since he placed a “No poop zone” sign outside his home and has been vocal about his opposition to a proposed dog park at Lacy Park.

But Kneier says he has no opinion about the dog park because it’s not up for City Council review. As for the sign, Kneier said it has been a sore subject for many neighborhood residents, who have pleaded with him to convince Lao to remove it.

“I personally don’t like the sign, but I can’t tell him to take it down,” he said.

Kneier has not talked to Lao, but sent him a letter of apology Monday, writing he and his wife “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," he continued. "This was a mistake, for which I apologize. It won’t happen again.”

Kneier said he did not realize he had “flicked” the bag onto Lao’s property because he was just trying to get rid of it.

“I didn’t think about it,” he said. “It was not premeditated. Nobody put a gun to my head and said put it down there.”

But Lao says he is not accepting Kneier’s apology because he believes the mayor is not being truthful.

“He is compounding the situation by lying about how this occurred,” Lao said.

Lao plans to take his grievances to the regular City Council meeting Wednesday.

The mayor of the affluent city of San Marino has apologized after he was caught on video tossing a bag of dog poop onto a neighbor's property, but the homeowner said Monday he was not satisfied with the city leader's response.