Iberia Parish Sheriff’s Office under scrutiny for treatment of inmates, others in custody _lowres (copy)

Advocate staff file photo by BRYAN TUCK -- The Iberia Parish Jail in New Iberia.

A trial scheduled to begin Tuesday in the only pending case in a federal probe of abuse and cover-ups at the Iberia Parish Sheriff's office has been postponed.

Mark Frederick, a former captain with the Sheriff's Office, is accused of assaulting an inmate at the Iberia Parish jail in 2011.

He was charged along with Sheriff Louis Ackal and 10 other deputies in an investigation that stretched to Ackal's first days in office in 2008.

Ackal was acquitted at trial last year, but the other 10 deputies have all pleaded guilty.

At a court hearing Monday, U.S. District Judge Donald Walter continued Frederick's trial without date over questions about his mental competency.

The judge ordered that Frederick undergo further mental evaluation by government doctors, and he put off a decision on whether the trial will move forward pending the findings.

The details, outlined in sealed court documents filed by Frederick's defense attorney asking for a postponement, were not discussed at Monday's hearing.

But Frederick has suffered extensive health problems, including brain cancer, and has difficulty concentrating or communicating for more than an hour or two, according to prior court filings by his attorney.

The federal investigation against Ackal included allegations he turned a blind eye and sometimes encouraged the abuse of inmates and the rough treatment of suspects in street-level narcotics enforcement.

Ackal, who remains sheriff, argued the abuses were carried out by rogue deputies who worked to conceal their actions.

Seven of the deputies who have pleaded guilty are scheduled to be sentenced Tuesday. 

Sentencing dates for the three others have been postponed because they are possible witnesses should Frederick stand trial.

Follow Richard Burgess on Twitter, @rbb100.​