The death certificate of Boston mob boss James “Whitey” Bulger revealed that the notorious criminal died last year from “blunt force injuries of the head.”

The document obtained by Fox News from the West Virginia Department of Health and Human Resources on Thursday showed that the 89-year-old was found dead on Oct. 30, 2018 at 8:21 a.m.

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He sustained injuries as a result of being “assaulted by other(s),” which occurred in his “prison cell” at the U.S. Penitentiary, Hazelton in Bruceton Mills, W.V., the certificate said.

The “final manner of death” was deemed to be a homicide, according to the document.

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The death of Bulger, who was a fugitive for 16 years and sentenced to life in prison in 2013, came after he was moved from a prison in Florida and had a stop in Oklahoma City before arriving at the high-security facility in West Virginia.

Fox News’ Ryan Gaydos contributed to this report.