Who was James 'Whitey' Bulger? One of the most notorious crime bosses in the country.

One of the most notorious crime bosses in the country, the powerful "Whitey" Bulger was killed in prison on Monday - the details are still unknown, but what is known is how Bulger lived his 89 year life.

James "Whitey" Bulger was born in South Boston- and developed a street sense early on, joining a gang and getting arrested, as well as spending time in jail - a pattern for Bulger throughout his life.

After two stints behind bars, Bulger returned to south Boston where he worked as a janitor and construction worker and then eventually a bookmaker and loan shark under the infamous Donald Killeen, who ran the South Boston streets for over 20 years.

Killeen was eventually murdered and Bulger joined Howie Winter's Winter Hill Gang - and started shaking down local bookies in the area.

In 1974 - Bulger for the second time was approached by the FBI to be an informant and this time accepted at the behest of John Connolly, a childhood friend and FBI Special Agent.

From then on Bulger had a man inside the federal government. A source of frustration for the Massachusetts State Police who were vigorously investigating the mobster.

Bulger, while an FBI informant, was "operating without any restrictions," according to Tom Foley a retired Col. in the Mass State Police told ABC News.

Foley added that the frustration became bigger than Bugler, because the FBI was letting him get away with crimes in an effort to nab members of the Italian organized crime family, or LaCostra Nosa. The FBI has not commented on these allegations.

Bulger's reign lasted until 1995 and he committed various illegal acts while the head of the Winter Hill Gang.

Interestingly enough, Bulger's brother, was the President of the Massachusetts State Senate and President of the University of Massachusetts. During Whitey Bulger's time of reign, Billy Bulger was the President of the State Senate.

In all, Bulger was proven to have killed 11 people, and while there was suspicion he was involved with another 7 murders, those could not be proven.

After 1995 Bulger went on the run for 15 years as the DEA began zeroing in on his illegal bookmaking operation, according to the Boston Globe.

He was captured in 2011, along with his girlfriend Catherine Greig, and tried in Boston in 2013 where he was convicted on charges including firearms possession and racketeering, which implicated him in 19 murders. Bulger was ultimately sentenced to life in prison.

Col. Foley said upon hearing of the death of Bulger he felt "good, a little bit for the families."