This guy was an old-school Chicago character. Don't think they make 'em like this any more.

Chicago man Mike Royko dubbed ‘the best crime researcher in America’ dead at 67 (Chicago Sun-Times)
Jimmy Agnew didn’t need Google.

Before the Internet, Mr. Agnew plucked literary gold from mountains of obscure resources to provide research to some of the nation’s top true-crime authors.

Legendary Chicago newspaper columnist Mike Royko once dubbed Agnew “the best crime researcher in America.”

Mr. Agnew, 67, died Thursday after battling pneumonia.

Tapping his police sources and well-informed bartenders and cabbies, his personal files of news clippings as well as little-known books, magazines and artifacts, Mr. Agnew did legwork for Charles Manson prosecutor and author Vincent Bugliosi, Chicago newsman Bill Kurtis and journalist Nick Pileggi, who wrote the book “Wiseguy,” which became the film “Goodfellas.”
“If Damon Runyon had chronicled Chicago — and done it a handful of decades hence — instead of Broadway in the ‘20s/’30s, he’d have based a character on Jim,” said celebrity profiler and author Bill Zehme. “He spoke Runyon fluently....broads and joints and dames and so on.”
A lengthy appreciation at the link above; worth reading.