PORTLAND (AP) - A Clackamas County prosecutor is taking part in the case against John Kerry.

Alfred French, 58, a senior deputy district attorney, appears in an ad that attacks the Democratic presidential contender's war record.

The ad features 13 Vietnam veterans who say Kerry has lied about his war record. The 60-second spot aired for seven days this month in Ohio, West Virginia and Wisconsin.

In the ad, French says: "I served with John Kerry. . . . He is lying about his record."

Kerry received a Bronze Star, a Silver Star and three Purple Hearts commanding a Swift boat in Vietnam. French, in an interview with The Oregonian this week, said Kerry lied about the circumstances that led to one of his Purple Hearts and a Bronze Star.

French said he is relying on the accounts of three other veterans.

"I was not a witness to these events but my friends were," said French, who was awarded two Bronze Stars during the war. "I believe these people. These are people I served with."

One of the men is Larry Thurlow, a leader of the veterans group and one of Kerry's most vocal critics. Thurlow, who served alongside Kerry, has disputed Kerry's claim that the senator's boat was under fire in March 1969 when he pulled Lt. Jim Rassmann out of the water.

But according to Thurlow's military records, obtained this week by The Washington Post, the five-boat flotilla was under enemy fire that day.

French, relying on friends' accounts, said Rassmann would have been picked up by another boat if Kerry had not helped. And French said any shots that were fired came from U.S. soldiers providing cover as Rassmann and two others were rescued.

"It's not like he wouldn't have been saved if Kerry had not been there," French said. "I don't believe they were under any fire when that happened. None of the other boats were damaged."

Rassmann, who lives in Florence and is campaigning for Kerry, said the ad is motivated in part by some veterans' anger over Kerry's anti-war stance upon returning home - a charge French acknowledges.

Rassmann said the group's claims are false.

"To come back 35 years later and conjure up fabricated stories is the lowest form of politics," Rassmann said.

"I honor these guys for their service," Rassmann said. "I know they were very courageous, along with John Kerry, and it saddens me that they are all at one another's throats."

French, a registered Republican, said he and Kerry served together in the same unit in January and February 1969, but he did not know him well.

French has spent most of his career in the Clackamas County district attorney's office. He is one of the prosecutors assigned to the double-murder case against accused child killer Ward Weaver.