In the first two months of its deployment to Iraq, the 3rd Battalion, 3rd Marine Regiment had lost three Marines out of its 1,000-member unit.

That number has doubled over the past five days.

Two Marines were killed Sunday while conducting combat operations, and a third was killed Friday in a "nonhostile" incident, the Pentagon said yesterday.

Lance Cpl. Jose S. Marin-Dominguez Jr., 22, of Liberal, Kansas, and Lance Cpl. Hatak Yuka Keyu M. Yearby, 21, of Overbrook, Okla., died while conducting combat operations in western Iraq.

Lance Cpl. Adam C. Conboy, 21, of Philadelphia, was killed by nonhostile fire, Conboy's mother said in a telephone interview yesterday.

"We were just told that it was nonhostile fire — that he was shot in the chest," said Mary Warner, Conboy's mother. "I feel heartbroken for the other Marine to have to live with that."

News of the three deaths came as about 200 Marines with the 1st Battalion, 3rd Marine Regiment from Kane'ohe Bay were expected to arrive home last night after five months in Afghanistan.

"As joyous as it is with our Marines coming home from Afghanistan, we still need to remember the three Marines that were lost this weekend and their families. They will be with us in our thoughts and prayers," said 2nd Lt. Binford Strickland, a base spokesman.

Yearby's family told KTEN TV in Oklahoma that he was a Native American dancer who performed around the world. They were notified early Sunday morning that his Humvee had struck a land mine.

Yearby was a warehouse clerk. He had joined the Marines in May of last year and reported to Hawai'i in October.

On a myspace.com account, Yearby described himself as a 5-foot-7, athletic Native American. Under a heading for children, he wrote, "some day." He said his interests were fishing, camping, spending time with his wife, family and friends. He listed his mother and father as his "heroes."

On May 11, three days before he died, his wife, Lindsey, wrote on the Web site: "Hey, baby ... can you believe that we have been married for 3 months and 1 day!!! I am soo happy you are in my life ... I can't wait for you to come home!!! I love you hubby!!!"

Above that, in an entry dated yesterday, a friend named Cody said, "Hey man, we had great times, parties at the river and even fun at work ... you will be missed greatly man. I'm sorry I didn't go with you. God man, I am so sorry. Please forgive me."

The 3rd Battalion, 3rd Marine Regiment has been operating in the Haditha area of Iraq northwest of Baghdad.

The base newspaper recently reported that the Marines deployed to the Euphrates River region of Iraq are focusing on showing Iraqi army soldiers and police how to spearhead security operations.

"The progress I have seen the Iraqi army make in the last few months makes me confident we can withdraw coalition forces from the area in the next six to eight months," said Lt. Col. Owen Lovejoy, the senior adviser for a military transition team.

Many Marines in the battalion arrived in Iraq in March, nine months after returning from a deployment to Afghanistan that went from November 2004 to June 2005.

A total of 56 Marines and three sailors based at Kane'ohe Bay have been killed in the Middle East since 2004, officials said.

Conboy's mother said her 6-foot-4 son loved the Marine Corps and talked to his parents at 17 about joining.

"We said you need to at least wait until you are legal age, and then he didn't do it until he was 20, but he did it by himself and then told us after the fact," Warner said.

Her son liked the Marines' reputation.

"They were the best, he believed," she said.

Conboy joined in March 2005 and reported to Hawai'i in September.

His mom said he had been in Iraq only eight weeks.

"He felt that it was his duty, that it was his generation's time to defend the country, and that's pretty much why he wanted to go," Warner said, adding she's taking the news of her oldest child's death "one day at a time."

She said her son was "just a great kid. He loved life, loved helping people. He loved to make people laugh."

She said political views on the war at this point for her are insignificant.

"I just want to say that I support his decision and if that's what he felt that he needed to do, that I support him and all the other troops that are over there," she said.

Next-door neighbor Linda Connor remembers Conboy playing basketball.

"He was always playing in the back with his friends, and whenever my dog would escape over there, he and his friends would bring him back," Connor said.

She remembers that even though he didn't know her very well when she moved in a few years ago, he'd always say hello.

"He was just a good kid," she said.

MarinDominguez joined the Marine Corps in 2003, reported to Hawai'i in 2004 and was a motor vehicle operator with the 3rd Battalion, 3rd Marines.

Reach William Cole at wcole@honoluluadvertiser.com.