The New York Times:

Allan A. Ryan, a Justice Department lawyer who in the early 1980s identified and prosecuted dozens of Nazi collaborators living in the United States, earning him a reputation as America’s foremost Nazi hunter, died on Thursday at his home in Norwell, Mass. He was 77.

His daughter, Elisabeth Ryan, said the cause was a heart attack.

***

Mr. Ryan employed a team of about 20 lawyers, 10 investigators and five historians, and sent them around the world to dig through archives and immigration records. Though he spent only a little more than three years in the office, he oversaw 700 investigations and 32 prosecutions. The New York Times called him “the nation’s foremost Nazi hunter,” but he insisted that most of his job involved mundane research.