Delaware prosecutors Monday mapped out their case against the first four inmates charged with the murder of Lt. Steven Floyd during a prison riot at James T. Vaughn Correctional Center last year, telling jurors that the attack unfolded in carefully planned phases.

In opening arguments, state Deputy Attorney General Nicole Warner described the “coordinated violence” of the 18-hour ordeal, and identified defendants Roman Shankaras and Dwayne Staats as having taken credit for masterminding a plot to overtake the prison's C-Building on Feb. 1, 2017.

“The attack was vicious,” Warner said. “It was tragically effective, and it was planned.”

According to prosecutors, a group of about 15 masked inmates overpowered Floyd, a veteran corrections officer, around 10:15 a.m., as he called them in from the unit's recreation yard. The prisoners then attacked Floyd with mop wringers and makeshift knives and threw him into a mop closet. He was found the next morning in an office, handcuffed and face-down in about two inches of water, Warner said.

Two other corrections officers were taken hostage and suffered serious injuries, but were later released during negotiations with the Delaware State Police. A fourth victim, prison counselor Patricia May, was freed around 5 a.m. Feb. 2, when authorities stormed the building and finally ended the riot. She was not physically harmed, Warner said.

Shankaras, Staats, Deric Forney and Jarreau Ayers have each been charged with murder, assault, conspiracy and riot, along with 12 of the other 126 inmates who occupied the medium-maximum security facility at the time of the takeover. Two other defendants face similar charges, but have not been charged with the most serious count of murder.

Warner said that all of the defendants had participated in a plot to gain seize control of C-Building, and that Shankaras and Staats both claimed responsibility for the “vision” behind the attack in the days that followed. Forney, they said, had personally assaulted the officers. Meanwhile, Ayers hinted in a call just one day before the uprising that “something big's about to go down,” and had “ordered” remaining inmates in from the yard after the assault began.

Shankaras and Forney are both represented by attorneys assigned by the Office of Defense Services. Staats and Ayers have elected to represent themselves at trial.

Jason Antoine, who is representing Shankaras, said his client believed that he was preparing to participate in a peaceful demonstration to protest prison conditions when things turned violent. He said that frustration had been “brewing for a long time,” but Shankaras has no personal vendetta against Floyd.

Shankaras, he said, was in the yard when another inmate told him that plans for a peaceful protest transformed into an armed takeover.

“It was supposed to be a stand-out in the yard to protest prison conditions,” Antoine said.

“All my client wanted was to be treated with dignity.”

The defendants on Monday challenged the credibility of the state's witnesses and said they would highlight the “inconsistencies” in the accounts that fellow inmates provided to investigators. In opening arguments, they focused especially on the role of Royal Downs, a prisoner in C-Building who they painted as the true ringleader of the uprising.

“The only thing consistent about this case is going to be the inconsistencies and contradictions,” Ayers said when addressing the jury.

Downs has taken a plea deal and is cooperating with the prosecution. He has not been charged with murder.

Superior Court Judge William C. Carpenter Jr., who is presiding over the case, said the proceedings are expected to last up to four weeks. The trial is the first of five that are planned to take place over the next four months for all 18 inmates that have been charged.