EVERETT — Prosecutors on Wednesday dropped the criminal case against a Marysville police officer who was tried in connection with the accidental shooting death of his daughter.

A judge earlier this month declared a mistrial after a Snohomish County jury was unable to reach a unanimous verdict. Seven jurors voted to acquit Derek Carlile. Four others believed he was guilty and one remained undecided after a day and a half of deliberations.

Snohomish County deputy prosecutor Lisa Paul on Wednesday said she opted to dismiss the second-degree manslaughter charge because she doubted that a second trial would result in a verdict.

“We don’t believe another jury would be able to reach a unanimous decision for either guilty or not guilty,” Paul said. “This is one of those cases where reasonable minds can truly differ.”

The veteran prosecutor spoke with jurors after the trial, but declined to comment on the discussion. She considered their feedback when deciding whether to retry the case, she said.

Carlile’s attorney, David Allen of Seattle, was pleased by Wednesday’s decision.

He said prosecutors did “a very professional job” at trial and made their best case, but the jury left no doubt how divided it was over whether the shooting was the result of criminal negligence or an accident that resulted from a brief lapse in judgment.

“Derek is a dedicated police officer. He takes responsibility for the terrible mistake he made,” Allen said.

The longtime attorney said he’s convinced that the evidence could be presented to multiple juries in multiple trials and there still would not be a unanimous verdict.

Snohomish County Prosecuting Attorney Mark Roe agreed that the facts of the case were mainly straightforward and uncontested.

“It was how the jury should interpret those facts that was at issue,” Roe said. “We don’t believe we could have tried the case any better with the evidence we had. There is no reason to expect to get a different result.”

Prosecutors alleged that Carlile acted with negligence on March 10 when he left a loaded handgun within reach of his four children, ages 1 to 7, while they were in the family van.

Snohomish County sheriff’s detectives believe that Carlile’s 3-year-old son, who was known to be fascinated with guns, grabbed a .38-caliber revolver from a cup holder next to the driver’s seat.

Carlile, 31, usually kept the gun in a holster on his ankle, but not that day. He also failed to engage the gun’s locking safety, or to store his off-duty weapon in the locking compartment on the driver’s door.

Carlile and his wife had exited the van to speak with a family friend. They were nearby when the fatal shot was fired.

The Camano Island father attempted life-saving efforts, but Jenna, 7, died at the hospital.

At trial, Carlile frequently wept as witnesses described what happened that day. Paul told jurors Carlile is punishing himself, but she also had urged them to hold him responsible for his daughter’s death. She said Carlile made a series of deadly decisions that led to the fatal shooting.

Allen argued that Carlile made a tragic mistake, but did not commit a crime. The shooting was an accident, not negligence, the defense attorney said.

To be convicted of manslaughter, jurors would have had to find Jenna’s death was the result of criminal negligence by Carlile.

Prosecutors on Wednesday stood by their decision to file the charge. They believed the case should be decided by a jury.

“We make decisions based on facts and the law, not the occupation of the participants,” Roe said. “There is ample history and evidence of that.”

Prosecutors in 2008 charged a Lynnwood grandmother with second-degree manslaughter after her 17-month-old granddaughter overdosed on methadone. The girl climbed out of her playpen and found the drug in her grandmother’s purse. The woman took responsibility for her granddaughter’s death, pleading guilty to the charge. She was sentenced to a month in jail and four months on a work crew with home-electronic monitoring.

In 2009, prosecutors charged an Everett police officer with murder for a fatal on-duty shooting outside a restaurant. A jury acquitted Troy Meade, but he later was fired from his job after an internal investigation found that he violated department policies during the shooting.

“Accountability can come from a whole lot more than a criminal conviction,” Roe said.

Carlile will remain on paid administrative leave pending the outcome of an internal investigation, Marysville police officials said Wednesday. An internal review was put on hold until the resolution of the criminal case. The department expects to determine if Carlile violated any policies and whether he should face any sanctions for the off-duty incident.

Allen on Wednesday said that he considers it a positive sign that Marysville police have kept Carlile on paid administrative leave.

Diana Hefley: 425-339-3463; hefley@heraldnet.com.