A mistrial was declared this morning in the trial of Jay D. Decker, who is charged with first-degree murder in the death of his 5-month-old daughter.Jurors left District Court around 10 a.m. after being dismissed by Judge Paula Martin.Prosecutors this morning were about to call their last witness, Coroner Erik Mitchell, when the defense made an oral motion for a mistrial, on the basis of “newly discovered evidence.” The state took no position on the motion, and Judge Martin granted it. The matter was discussed in Martin’s chambers, not in open court. Martin, assistant Dist. Atty. Amy McGowan, and Decker’s defense attorneys all said they would not discuss what the evidence was. McGowan cited “new evidence and legal reasons,” but she would not elaborate on what happened.”A request for mistrial was made this morning because of some new evidence that has come to light, and it was granted,” defense attorney Tom Bartee said.A new trial for Decker was scheduled for Nov. 13. -Contributed by Eric Weslander.