Read: Blood Relation by Eric Konigsberg, 2005, 9780060099046.
Pretty good but leaves me wanting to know more. Konigsberg grew up in Omaha and ended up in NYC working as a writer. After working for a writer and journalist for a time he gets a phone call from an unknown and imprisoned great uncle.
Harold "Heshy" Konigsberg was a loanshark and hired killer in New Jersey until his 1967 (or about then) imprisonment for extortion and a later 1983 (or about then) conviction for murder. The rest of the Konigsberg family has ignored the unpleasant Heshy and downplayed his crimes. Eric is intrigued by this and starts to interview Harold in Auburn Correctional Facility in New York.
Eric writes about Harold, the Konigsberg family, Harold's crimes, his murder trials (Harold admitted to 20 murders to the FBI but was only brought up on one murder - with a retrial), and Harold's psychopathic behavior. Harold is insane. Even as a 70 year old convict his murderous ability scares the hell out of Eric; Harold threatens to rip Eric's eye out, tear his head off, and all sorts of other threats.
The problem is that this isn't a biography. Even though Eric does a marvelous job in researching Harold there is only so much information he can get a hold of. What started out as a magazine article ended up as a really long magazine article. Eric interviewed relatives, FBI agents, family of Harold's victims and even Harold's mob associates. He gained access to FBI agents' interview notes prosecution case files. But, nobody, Harold in particular, are going to say much about Harold's many murders for hire. Harold's many other crimes like loansharking, drug dealing, extortion, robbery, burglary, porn operations, etc. are mentioned but there are no decent stories behind them.