SAN DIEGO — A Marine accused of murdering Iraqi civilians, including children, in the town of Haditha should have all charges dropped against him because of weak evidence, an investigating officer recommended on Thursday.

Lance Cpl. Stephen B. Tatum, 26, is charged with unpremeditated murder of two girls and negligent homicide on suspicion that he unlawfully killed two men, a woman and a boy. He is also accused of assaulting another boy and a girl.

The investigating officer, Lt. Col. Paul Ware, said the evidence was too weak for a court-martial. Tatum, of Edmond, Okla., shot and killed civilians, but "he did so because of his training and the circumstances he was placed in, not to exact revenge and commit murder," Ware wrote.

"I believe ... Tatum's real life experience and training on how to clear a room took over and his body instinctively began firing while his head tried to grasp at what and why he was firing," Ware wrote. "By the time he could recognize that he was shooting at children, his body had already acted."

Ware's recommendation is nonbinding. Lt. Gen. James Mattis, the commanding general overseeing the case, has final say about whether Tatum will be court-martialed.

If Mattis accepts the recommendation to dismiss charges — as he has with three of eight Marines who were initially accused — that would leave one Marine charged with murder. Staff Sgt. Frank Wuterich, the squad leader, is charged with the unpremeditated murder of 18 men, women and children. He is scheduled to appear in court Aug. 30 for a preliminary hearing.

An attorney for Tatum, Jack Zimmerman, said he was pleased with the recommendation and would not comment further until he knew that the general had seen the 29-page report.

Ware said the deaths were tragic and that photographs of the victims were "heart wrenching" but that Wuterich fired first inside one room where seven Iraqis were killed, with Tatum following his lead.

Tatum was "entitled to act on his honest and reasonable belief" that Wuterich was firing at legitimate targets, Ware wrote.

A message left for Wuterich's attorney, Neal Puckett, wasn't immediately returned.

The victims died when a Marine squad launched a house-to-house assault Nov. 19, 2005, following a roadside bomb blast that killed a Marine driver.

Tatum was among four Marines charged with murder, while four others were charged with dereliction of duty for failing to investigate the deaths.

Of the four accused of murder, prosecutors dropped charges against Sgt. Sanick Dela Cruz and gave him immunity to testify.

Mattis has dismissed charges against another rifleman, Lance Cpl. Justin Sharratt, after an investigating officer also recommended against sending him to a court-martial.

Squad leader Staff Sgt. Frank Wuterich still faces murder charges. He is charged with the unpremeditated murder of 18 men, women and children and is scheduled to appear in court Aug. 30 for a preliminary hearing.