Here is the article:

S.F. police union accuses Ayers in 1970 bombing

They are discrediting the source:

The union leveled the charge in a letter to a conservative organization lobbying for arrests in the case, but said it had not been in contact with investigators and had no new evidence related to the bombing, which killed Sgt. Brian McDonnell.

Instead, the union cited information from a former Bay Area resident, Larry Grathwohl, who is working with the conservative group, America’s Survival Inc. of Maryland. Grathwohl asserts that he infiltrated the Weather Underground as an FBI informant and heard Ayers confess to a role in the bombing.

Ayers has denied any involvement in the bombing and, in January, called Grathwohl a “paid dishonest person” in an interview with The Chronicle.

The union’s accusation surprised some authorities. According to a source familiar with the probe, who spoke on condition of anonymity, investigators have found no evidence that links the Weather Underground to the bombing.

and…

In addition to running America’s Survival, Kincaid is the editor of a conservative organization called Accuracy in Media. He has attempted to link Obama to communism and socialism.

He also has views that might be considered extreme in San Francisco, such as calling for a “quit gay sex” campaign. “It appears that the homosexual lifestyle is as addictive as smoking,” he once wrote.

Kincaid said he was not going after Ayers to hurt Obama, but added, “We are concerned that we now have an attorney general who was involved in Clinton administration pardons of members of the Weather Underground.

“Ayers, an education professor at the University of Illinois at Chicago, did not return a call Wednesday. Dohrn, a law professor at Northwestern University, was out of the country.”