The vandals who desecrated the graves of U.S. veterans over the Memorial Day weekend were professionals, says a Vietnam vet who kept night watch at the cemetery in Washington State.

"We thought at first it was just a prank-type deal at first. We were very upset about it and so forth, but now we know that this is a real deal," said David Resch, a past commander of American Legion Post 93 in Eastsound, Wash. "This is a Nazi act, not just somebody going out there and desecrating things for the fun of it."

No one has taken responsibility for back-to-back flag desecrations at the Woodlawn Cemetery in Orcas Island, Wash., according to San Juan County Sheriff Bill Cumming.

"It's speculative at this point to assign it to an organized group or juveniles that for some reason wanted to shock the community," Cumming said.

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On Sunday morning, members of the Boyle B. Martin American Legion post found desecrated the flags of 97 veterans. Of those, 46 flag standards were empty, 33 contained burned flags and 14 had been replaced with handmade swastika flags, authorities said.

Resch kept watch early Monday after legionnaires replaced the flags, but the vandals struck again under the cover of darkness.

"I didn't see anybody," said Resch, who told FOXNews.com that he kept watch from 12:30 a.m. to 4:40 a.m. "They're very professional."

Thirty-three flags had been replaced with hand-drawn swastika flags, according to the San Juan County Sheriff's Office in Friday Harbor, Wash.

"The scale and the tenacity and the timing, I don't think this is the work of one person," Cumming said. "We think it's more than one."

Officials are trying to get physical evidence, such as fingerprints, from the paper and duct tape left behind.

The crimes have stunned this small community of approximately 5,000 people.

"It's a small island, and I think if it's local folks that did it, everybody kind of talks to everybody about certain things, you know," said Pierrette Guimond, district commissioner for San Juan Cemetery District No. 3, which includes Woodlawn.

It's the first act of vandalism to take place in the cemetery, she said.

"If people want to protest something this is not the place to do it," Guimond said. "People go there to think about the people that went to war for their country and stuff like that. It's a really sacred place."

The vandalism is considered a hate crime under Washington state law, Cumming said.

A spokeswoman for the Department of Veterans Affairs said the federal government does not have jurisdiction in the case.

"We don't have jurisdiction over issues of vandalism because it's a veterans' grave in a private, community cemetery," said Jo Schuda, a VA spokeswoman. "If it was in a federal cemetery, it would be a federal crime subject to potential charges brought in federal court."

Despite the vandalism, Post 93 performed its Memorial Day tributes Monday afternoon, including playing "Taps" at the cemetery. Around 75 people turned out for the ceremony.

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