A military judge Wednesday found a Marine Corps swim instructor not guilty of negligent homicide in the drowning of a recruit last year.

Staff Sgt. Nadya Lopez had been accused of failing to recognize or ignoring signs that Jason Tharp, 19, was too tired or incapable of continuing before he drowned during training in a pool on Feb. 8, 2005.

But the judge, Maj. Mark Griffith, acquitted Lopez in the nonjury court-martial just 40 minutes after defense attorneys rested without calling any witnesses. They contended prosecutors simply failed to prove their case.

"Sadly Marines do die in training," Lt. Col. Scott Jack told the judge in the defense's closing arguments. He added that Lopez "did nothing wrong. She was a professional water combat survival instructor."

Tharp's mother, Linda, cried as the verdict was read and told the judge, "I hope you see Jason every time you turn around and hear him screaming."

Tharp's father, Johnny, fought back tears and said: "Our son just got killed again."

Several Marines testified that Tharp, of Sutton, W.Va., did not want to go in the pool and yelled loudly to get out during a survival floating exercise in his fifth week of basic training. Tharp was apparently unhappy as a Marine and had written home several times that he wanted to be discharged.

After the verdict, Lopez said the judge's decision shows Tharp's death was an accident "just like the autopsy report reported."

When asked if she had anything to say to Tharp's family, Lopez said, "I'm sorry for their loss. I wished he hadn't died. They are in my prayers."

If convicted, Lopez could have faced a dishonorable discharge, forfeiture of all pay and confinement for three years.

In closing arguments, prosecutor Capt. Doug Hatch told the judge Lopez was negligent for not getting Tharp out of the water.

The government did not contend Lopez was a bad swim instructor, Hatch said, but "she was negligent on this one day. She failed. She failed her fellow instructors in the pool, she failed the Marine Corps and she failed Jason Tharp."

Earlier, some prosecution witnesses testified that none of Lopez' methods seemed unsafe.

"He (Tharp) didn't seem necessarily scared of the water. It seemed like he really wasn't trying," said 1st Lt. Randy Brown, the safety officer at the pool that day.

But Lance Cpl. Bradley Kilgore testified Tharp clearly did not want to go into the water. "He was kind of making a scene. It was hard not to notice," Kilgore said.

As Tharp continued to yell, the sergeant in charge of the pool, Sgt. Anthony Davis, said he told Lopez to take him out of the water.

"I said, 'Get him out of the pool. ... He just quit. He doesn't want to do it,"' Davis testified.

Davis said he saw Tharp's head go under the water but that Lopez was always close by. He added that as Lopez helped Tharp to the side of the pool, she asked Davis, "Does he look pale to you?"

Davis said they noticed Tharp had a weak pulse and they began trying to resuscitate him. The recruit died a short time later.