The state multi-county grand jury heard more testimony a few weeks ago about the Oklahoma County Jail.
The grand jury could issue a report on its findings in March or April.
The activity comes as the trust that oversees jail operations has been hit with two new federal civil rights lawsuits.
Testifying recently were Jim Couch, the former trust chairman, and Rev. Derrick Scobey, a new trustee who pushed for the firing of the jail administrator.
The jail administrator has resigned, too.
Also appearing was former Oklahoma County District Attorney David Prater, who in 2021, called for an investigation of the jail after health inspectors found unsafe conditions there.
Grand jurors hear testimony in closed sessions, and witnesses are instructed they cannot disclose anything. Special prosecutor Jack Thorp declined comment Wednesday.
The trust took over the jail on July 1, 2020, after promising conditions would improve.
It has faced harsh criticism through out its time in charge, though, primarily because of the high number of inmate deaths.
The inmate death toll under the trust is now nearly 40.
The jail administrator, Greg Williams, announced his resignation in December, a month after Trustee Scobey sought to have him fired because of the deaths. Mr. Williams’ last day was Jan. 19.
Mr. Couch, a former city manager in Oklahoma City, left the trust in December. In a farewell email, he pointed to a series of accomplishments at the jail under the trust despite the pandemic and understaffing.
“There is a new culture amongst the detention officers to care for the detainees,” Mr. Couch wrote.
Rev. Scobey, the pastor of the Ebenezer Baptist Church, was appointed to the trust in September, but will have to leave in April if he wins his bid to be Oklahoma County clerk.
He also testified before grand jurors Nov. 9 after they heard that day from four other trustees.
Mr. Prater, who repeatedly criticized the trust, retired last month after serving 16 years as district attorney.
An Oklahoma County grand jury was convened in 2021 at Prater’s request to look into issues with the jail.
The special prosecutor decided to use the multi-county grand jury instead.