A US State Department whistleblower whose personal email files contained allegations of abuse and wrongdoing has had his account hacked. Four years of potential evidence has been deleted, his lawyer announced.

A computer attack of unknown origin appears to have targeted Richard Higbie, a criminal investigator with the Diplomatic Security Service who earlier this year accused the State Department of blocking his career advancement.

Cary Schulman, Higbie’s lawyer, told the New York Post that Higbie’s Gmail account included correspondence with other whistleblowers about top officials within the State Department and members of Congress who are investigating the matter.

“They took all of his emails and then they deleted them all,” Schulman said. “Obviously somebody is not happy with something he’s doing and wanted to get that information and also cause him an inability in the future to have ready access to that.”

The lawyer said that the hack was “sophisticated” and “alarming,” adding that the messages also contained notes between he and Higbie on their legal strategy.

Higbie is one of the State Department officials who reportedly informed the agency’s inspector general about a variety of wrongdoings earlier this year. The inspector general’s annual report, of which Higbie was as a source, chronicled reports of officials soliciting sex from foreign prostitutes in a public park (some of whom were underage), an “underground drug ring” that funneled illegal substances to security teams in Iraq, and at least one instance of an official over-charging the State Department for the number of hours he worked.

Higbie worked closely with fellow whistleblower Aurelia Fedenisn, although the two now maintain that they were instructed to stop investigating because of how embarrassing the revelations would be, and how many careers would be at risk.

Fedenisn told CBS that when the final report was shown to department higher-ups, one said, “this is going to kill us.” When the inspector general report was published, all references to specific cases had been scrubbed, she added.

“My heart really went out to the agents in that office because they really want to do the right thing. They want to investigate the cases fully, correctly, accurately – and they can’t,” Fedenisn said.

The State Department issued a statement this summer claiming that “not all allegations are substantiated. It goes without saying that the Department does not condone interference with investigations with any of its employees.”

Schulman told the Post that this hack comes after his law firm was broken into just after the State Department accusations were made public. Oddly, the burglar sawed a hole in Schulman’s wall only to steal his computers. Other valuables were left behind. Police later arrested a suspect, but Schulman has since admitted lingering skepticism.

“We feel like we’re in a movie. It’s nuts,” the attorney said. “It makes us wonder…maybe we’ve got something we don’t even realize or maybe they’re worried about something.”