State prosecutors are seeking a new death penalty trial for Christopher DiMeo, who received a life sentence in the killing of two Fairfield jewelers last week.

In a motion filed Tuesday in Superior Court, Senior Assistant State's Attorney Joseph Corradino contends the prosecution is entitled to a new trial on the death penalty because the jury failed to render a unanimous verdict.

Corradino declined to comment on the motion. DiMeo's lawyers were unavailable for comment.

A 12-person Superior Court jury last Friday determined that DiMeo should get life in prison rather than the death penalty for the Feb. 2, 2005, murders of Fairfield jewelers Kim and Tim Donnelly in their Posr Road shop.

But in its verdict the jurors said they were hung on one of two aggravating factors -- whether DiMeo engaged in intentional conduct that inflicted extreme physical or psychological pain, suffering or torture on Kim Donnelly above and beyond that necessary for the killing.

Corradino's motion said Judge Robert Devlin was obligated to declare a mistrial after the jury hung on the one aggravating factor under state law, but refused to do so.

"The denial of a motion for a mistrial is an error, which was materially injurious to the state," he wrote.

The motion is expected to be heard on May 6 when Devlin is scheduled to sentence DiMeo to life without the possibility of release in accordance with the jury's verdict.