CHICAGO (CBS) —  CBS 2 has learned the cellmate of an inmate found beaten to death was recently involved in a violent fight at the Cook County Jail.

CBS 2’s Suzanne Le Mignot is always investigating and asked if the two men should have been in the same cell.

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Cook County Jail inmate Pedro Ruiz was found beaten inside his cell Saturday. He was pronounced dead at a hospital.

Sources with knowledge of the incident told CBS 2 Ruiz’s cellmate was among the five inmates caught on surveillance video attacking another inmate in the jail day room, last November. The inmate is kicked and punched repeatedly.

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After the attack, a joker from a deck of playing cards, is thrown on top of the injured inmate.

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Sources said this is significant, pointing to ongoing feuds taking place inside the jail between different gangs.

Arrest reports CBS 2 found in court documents show the beating victim, Ruiz, and his cellmate are members of different street gangs.

Illinois county jail standards state gang activity must be considered when an inmate is assigned to their cell.

So why was Ruiz assigned to a cell with an inmate from another gang? Especially after the recent attack in the jail day room?

CBS 2 asked the jail why they put two rival gang members in the same cell. The jail said there hasn’t been a homicide in the jail in more than five years and they are conducting a thorough review of the incident.

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The state’s attorney’s office said there have been no charges in Ruiz’s death yet. Police are still investigating.

Suzanne Le Mignot