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.

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.

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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.