BOSTON (CBS) – Whitey Bulger’s reported killing in a West Virginia prison Tuesday is the third inmate killing this year at the high-security facility.

Just five days ago, five members of Congress sent a letter to Attorney General Jeff Sessions concerning “dangerous continual understaffing” at prisons in Pennsylvania and West Virginia, including USP Hazelton where Bulger was found dead.

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USP Hazelton in West Virginia (WBZ-TV)

The letter calls for the hiring of more full-time correctional officers and details two recent killings at Hazelton.

“In April 2018, an inmate at FCC Hazelton in West Virginia was mortally wounded in a fight that erupted in one of the housing units and died shortly thereafter. Last month, another inmate was killed at the same West Virginia facility, marking the second homicide in that facility in just five months,” the letter states. “This is unacceptable.”

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The president of the correctional officers union in Hazelton spoke with WPRI-TV.

“This is the third homicide in seven months at our facility,” Richard Heldreth told the TV station on Tuesday. “We are very understaffed, we are short about 40 officers.”

According to the Boston Globe, a “fellow inmate with Mafia ties” was being investigated for Bulger’s death.

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Hazelton houses 1,277 male inmates.