CHICAGO (CBS) — Two days after a teenager was beaten to death inside the Cook County Jail, CBS 2 is investigating another disturbing attack that seriously injured a different inmate.

In this CBS 2 exclusive, Suzanne Le Mignot is digging into what’s going on behind bars.

On Saturday, inmate Pedro Ruiz was found beaten in his cell at the Cook County Jail. He was taken to a hospital and pronounced dead.

Sources with knowledge of the investigation said Ruiz’s death is one of several incidents of violence in the jail in recent months.

Surveillance video from a jail day room from less than three months ago showed an inmate is punched and kicked repeatedly by five other inmates. A soap sock, that’s a sock filled with bars of soap, is also used in the beating along with a weapon.

As the pool of blood around the man’s head grows, an inmate throws a joker card, from a deck of playing cards, on top of him.

Those sources said that’s significant, indicating there are ongoing feuds inside the jail taking place between different gangs.

All five of the people involved in the incident have been charged with attempted murder. An internal investigation is also taking place.

CBS 2 has been exposing the violent beatings taking place on Cook County Jail buses for several months.

Back to that video, inside the day room, shows similar violence inside the jail. Nearly seven minutes after the beating ended, Cook County Sheriff staff enters the day room. Inmates are cuffed. So is the victim. He’s taken to a hospital and treated for puncture wounds to his head, neck and back.

The police report said the officer that had been assigned to the area was securing inmates in another part of that section of the jail, when the attack happened.

CBS 2 asked if staffing shortages played a role in this incident and why it took seven minutes for staff to respond. CBS 2 was told staffing was not an issue in the November incident.

As for Ruiz’s death, the jail said it is under internal investigation.