LOS ANGELES (CBS) — The FBI is looking into beatings at the men’s jail in downtown LA in a case that could have major ramifications for the sheriff and county.

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All cellular phones are banned from inmates, but according to law enforcement sources, the FBI smuggled a phone into an inmate who was working as an informant for the FBI.

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He used the phone to report back to the FBI about alleged beatings and mistreatments of inmates that he either witnessed or heard about.

Inmates with apparent mental disabilities are more sought after by guards because of their lack of understanding simple commands, the undercover inmate reported.

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The investigation has gone on for months and it is unknown as to when it will be completed.