An inmate being tried for the murder of a correctional officer during a riot at Delaware's maximum-security prison was the "puppet master" of the uprising, a convicted murderer who also participated in the riot told jurors Wednesday.

Royal Downs, a former Baltimore gang member serving a life sentence, also testified about two prison letters that Roman Shankaras wrote to him after the February 2017 riot in which prison guard Steven Floyd was killed. Two other guards were released by inmates after being beaten and tormented. A female counselor was held hostage for nearly 20 hours before tactical teams burst in and rescued her. Sixteen of the inmates were charged with murder.

In sometimes rambling, disjointed sentences, the letters from Shankaras describe details of the riot and of prior discussions among a small group of inmates, noting that "persistence procreated the resistance."

"Some had to be convinced, some had to be tricked, and others had to be forced," Shankaras wrote.

Downs testified, however, that he never saw Shankaras take part in any violence, and that Shankaras mostly stayed in his cell.

"For lack of a better word, I guess I would say 'puppet master,'" Downs replied when asked by a prosecutor what role Shankaras played in the riot.

"Everything, I believe, was ran through him," Downs said.

Under cross-examination, however, Downs testified that he wondered why Shankaras would get involved in the uprising, given that he had only a short time left on his sentence. Downs indicated that he thought a protest of prison conditions should be handled by inmates serving life or other long sentences.

"I didn't agree with him getting caught up in it," Downs said of Shankaras.

Shankaras, 32,recently completed a 7-year sentence for unrelated riot and robbery charges. He is being detained on $2.8 million cash bail on the prison riot charges. He is charged with murder, assault, kidnapping, conspiracy and riot.

Shankaras was one of 18 inmates indicted after the riot, 16 of whom were charged with Floyd's murder.

The first two trials against seven inmates resulted in only one — who admitted planning the uprising — convicted of murder. Downs' cellmate, Kelly Gibbs, killed himself in November, just days after pleading guilty to rioting, kidnapping, and conspiracy.

In March, prosecutors dismissed cases against six of the remaining inmates, opting to move forward only against Shankaras and two others.

Downs, meanwhile, pleaded guilty to a single count of riot shortly after a grand jury issued an indictment in late 2017, agreeing to testify against other inmates.

With little physical evidence, and no surveillance camera footage, prosecutors have relied heavily on testimony from Downs and other inmates, whose credibility has been successfully attacked by defense attorneys.

Downs has claimed repeatedly that he advocated for a peaceful protest as a way inmates could air grievances about their treatment, perhaps by staying in their cells and refusing to come out. He claims he was overruled by other inmates who wanted to take over the building where they were being held.

Once the riot broke out, however, Downs became a key player, taking a walkie-talkie from another inmate and participating "for a long period of time," he said, in hostage negotiations with law enforcement officials. Downs testified that he later told police that, in deciding to take a central role in the incident, he had to put on his "O.G.," or "original gangster" face.

"I got involved for the most part to save lives," he said.

As the siege ended, Downs began cooperating immediately with investigators, telling them that he knew what happened and wanted to talk to a prosecutor.

Downs said that after receiving the letters from Shankaras two months after the riot, he hid them in his cell and later smuggled them out to a family member, knowing they could prove useful to him.

"I held on to them because I knew I was going to be charged. ... It was clear my involvement in this," he said.

Downs later pleaded guilty to a single count of riot and agreed to testify against other inmates.