After a series of trial losses against inmates accused in deadly rioting at Delaware's maximum-security prison in 2017, authorities said Wednesday that they will not pursue any more prosecutions.

The decision comes less than three weeks after former inmate Roman Shankaras, who was accused of leading the riot, was acquitted on charges of murder, assault, kidnapping, riot and conspiracy.

Shankaras' acquittal came after two previous trials against seven other inmates yielded just one murder conviction — against a convicted killer who boasted in court of planning the uprising, knowing it could turn violent. Those trial failures prompted prosecutors in March to dismiss cases against six other inmates, opting to move forward only against Shankaras and two others.

On Wednesday, prosecutors said they would not try Lawrence Michaels or Alejandro Rodriguez-Ortiz. They also will not pursue a retrial of Obadiah Miller on riot and murder charges after jurors could not reach verdicts on those charges in his trial earlier this year.

"I'm happy for the guys, that justice is being done on behalf of them," Shankaras said, adding that he remains concerned that the accused inmates will be mistreated by prison guards, despite not being found guilty in correctional officer Steven Floyd's death.

"Normalcy will never exist for them ... I'm going to advocate for their safety," Shankaras said.

Shankaras, who had completed a seven-year sentence for unrelated riot and robbery charges, was released from custody hours after his acquittal last month. He criticized prosecutors for abusing their discretion, starting with the "wide net they cast" to obtain indictments against 18 inmates in October 2017.

"They acted stubborn," he said, adding that prosecutors acted with a sense of entitlement because they are used to getting their way in the courtroom.

Democratic Attorney General Kathleen Jennings, through a spokesman, refused to speak with The Associated Press. In a statement, her office said prosecutors did "herculean work," and that their adherence to ethical standards was "unwavering." Officials said no inmate prosecution witnesses were offered favorable treatment in exchange for their testimony, and they rejected any implication that any witness was pressured to testify.

The only guilty verdicts prosecutors were able to obtain came against two inmates who represented themselves at trial. Self-proclaimed riot leader Dwayne Staats, who is already serving life for murder, was convicted of murder, riot, kidnapping, assault, and conspiracy. Jarreau Ayers was convicted of riot, kidnapping, assault, and conspiracy. A third defendant, Kelly Gibbs, killed himself in November, days after pleading guilty to rioting, kidnapping, and conspiracy.

"Nevertheless, three juries have since shown that proving beyond a reasonable doubt who was responsible for Lt. Floyd's death is no longer possible," Jennings' office said.

Eighteen inmates were indicted after the February 2017 riot, 16 of whom were charged with murder in Floyd's death. 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.

The defendants were all assigned private attorneys hired at taxpayer expense because of conflicts of interest involving public defenders. The cost to Delaware taxpayers had risen to about $1.3 million even before Shankaras went on trial.

"The defense attorneys worked long and hard to protect the rights of the accused," said Brendan O'Neill, chief of the Office of Defense Services. "These were serious charges and the defendants are extremely fortunate."

With little physical evidence, and no surveillance camera footage, prosecutors relied heavily on testimony from other inmates, whose credibility was successfully attacked by defense attorneys. With no definitive proof of which inmates attacked Floyd, they argued that anyone involved in the riot could be convicted under the "accomplice liability" doctrine. Under that rule, a person who agrees to commit a crime, such as a riot, can be found guilty of other crimes that could reasonably be foreseen as arising from that initial course of conduct.

The prosecution's star witness in all the trials was former Baltimore gang leader Royal Downs. Downs, serving a life sentence for murder, claimed that he advocated for a peaceful protest by inmates to air grievances about their treatment. Once the riot broke out, however, he became a key player, taking a walkie-talkie from Staats and participating in hostage negotiations with law enforcement officials.

Despite his role in the riot, Downs was among several inmates allowed to leave the building during the siege. He signaled his willingness to cooperate with authorities even before the riot was over and subsequently pleaded guilty to a single count of riot, which carries no mandatory prison time.