Marine Lance Cpl. Roger W. Muchnick Jr. had survived deployments to the dangerous Middle East, but the 23-year-old former Westport resident's life was tragically cut short while training on home territory Monday when he and six fellow Marines were killed by a mortar explosion.

Muchnick, a 2008 graduate of Staples High School, and the other Marines died from injuries suffered during a training exercise at the Hawthorne Army Depot when a 60 mm mortar shell exploded in its launch tube. They served with the 2nd Marine Expeditionary Force based at Camp Lejeune, N.C.

News of Muchnick's death cast a pall over Staples High, where he was remembered as gregarious and well-liked, a young man who harnessed his natural athletic abilities to focus on academics as well.

Muchnick -- "R.J." to his family -- who served tours of duty in Afghanistan and Kuwait, was the eldest of four children raised by Kate Coakley, now of Jupiter, Fla., and her ex-husband, also named Roger, who moved to North Carolina. The couple's other children are son Will, who also attended Staples, and twin daughters, Grace and Avery.

Originally from Weston, Muchnick moved to Westport when he was in middle school, attending the seventh and eighth grades at Coleytown Middle School. He then briefly attended Fairfield College Preparatory School before transferring to Staples during his sophomore year.

At Staples: `Empathetic, tough, electric'

In his early days at Staples, Muchnick frequently sought the support of Assistant Principal Karyn Morgan.

"We were very close -- I got to know who he really was," Morgan said Thursday. "I got through that tough exterior and learned that he was a very sensitive and empathetic young man. I almost felt like a second mother to him."

Morgan also shared an anecdote from the 2008 graduation ceremony in the Staples fieldhouse, which she called her favorite memory of Muchnick: "After he received his diploma and crossed over that little bridge that we have, he literally picked me up and swung me around and gave me a big bear hug," she said. "That touched me."

Morgan stayed in touch with Muchnick after he graduated. A year after his high school graduation, Muchnick wrote Morgan a "beautiful" letter, the assistant principal recalled. She pointed, in particular, to a quote from an unnamed source that Muchnick included in the letter: "None of us got where we are today solely by pulling ourselves up by our bootstraps. We got here because somebody bent down and picked us up along the way."

Morgan added that Muchnick concluded his letter to her with a powerful message: "You have made a lifelong friend in me, Mrs. Morgan, and I truly mean it when I say that if you ever need anything I'll always be there for you, like you were there for me."

Staples Principal John Dodig on Wednesday recalled Muchnick as outgoing and popular.

"He was the kind of kid, who if he ever decided to become a salesman, there'd be no stopping him," Dodig said Wednesday. "He had an electric personality."

Mourned by many friends

On his Facebook page, Muchnick has several hundred friends listed. And he knew every single one of them, his mother said Wednesday.

"R.J. was one of the most social people you ever met. He has friends who he's known since he was 2 years old. He has friends from preschool and all the way up through Staples and beyond," Coakley said. "He's never lost a friend. Not his whole life."

While at Staples, Muchnick was a linebacker and running back for the school's football team and also played lacrosse. In a 2008 profile of Muchnick in the Westport News, he talked about the benefits he found in playing both sports: "Playing football and lacrosse year-round makes you into a better athlete."

On the lacrosse and football fields, Muchnick forged close friendships with teammates. In interviews Wednesday, several remembered him as a highly competitive and driven player, and a charismatic and ebullient presence off the field.

"Everyone always liked Roger and gravitated toward him -- he was never at a loss for a joke," recalled Jason Zins, a friend and lacrosse teammate since the time Muchnick enrolled at Coleytown Middle School. "But he also really hated to lose. He really pushed everyone around him to be their best. And he always had the best shot on the team."

Dylan Bobrow, who played lacrosse and football with Muchnick from seventh grade until they graduated from Staples five years ago, said Muchnick was an exemplar of commitment and national service when he decided to become a Marine.

"He was very passionate about the Marines and his country," Bobrow said. "He was in good spirits and he was excited about his training. Unfortunately, he died doing it, but at least he died doing what he loved."

An athlete from youth

Muchnick was a versatile athlete from his childhood. He was a Little League pitcher until fifth grade, and began playing football when he was in third grade. He also played basketball from kindergarten to sixth grade.

In the 2008 interview with the Westport News, Muchnick discussed his love of lacrosse.

"I was playing it since I was little and when I got to high school, I loved it and I kept playing it," he said.

At Staples, in addition to academics -- he had a 3.5-grade point average -- he concentrated on lacrosse and football.

"I've been doing it for so long and it has become second nature for me," Muchnick told the Westport News.

He was not as big as many of the opposing players, Muchnick admitted, which convinced him that, on the field, "You have to be meaner than them."

"I just got to work hard because I'll face much bigger opponents," he added .

Those words squared with memories of Muchnick as a youngster by Joyce Colwell, a longtime family friend.

"He was a competitive person," said Colwell, a longtime family friend. "He was personable and he looked out for others. He had a lot of compassion, and when all of our kids were growing up in Westport, he always looked after the younger ones. He made sure that whatever was going on, they didn't get left out."

The structure and the team-building aspects of the Marines, Colwell said, are facets of the military that dovetailed well with Muchnick's personality.

"I've known him from the time he was 2 years old. He was a leader even as a kid. He was very determined, and he showed empathy toward others," Colwell said. "Being the eldest of four kids, he was a wonderful big brother, always looking out for people."

After Staples, Muchnick went on to attend Eastern Connecticut State University, where his biography on the university's website said he was a four-year member of the lacrosse and football teams.

In that biography, he answered the question, "One thing you would like to do before you die?" with the simple statement: "Live."

Marine Corps honors

He joined the Marine Corps in June 2010 and was promoted to his current rank in May 2011. Muchnick's military awards include the Combat Action Ribbon, National Defense Service Medal, Afghanistan Campaign Medal, Global War on Terrorism Expeditionary Medal, Global War on Terrorism Service Medal, Sea Service Deployment Ribbon, and NATO Medal-ISAF Afghanistan.

He was most recently deployed in support of Operation Enduring Freedom in 2011.

"Our hearts, thoughts, and prayers go out to the families and friends of our fallen angels," Lt. Col. Andrew J. McNulty, the commanding officer of the 1st Battalion, 9th Marine Regiment, said in a statement Thursday.

"Currently, there are several teams of investigators already on site, working around the clock, to determine what happened so we can prevent it from happening again. We do not know what caused the mortar system failure," he said of the accident that killed the seven Marines.

Gov. Dannel P. Malloy on Thursday ordered flags to remain at half-staff in honor of Muchnick.

"Lance Corporal Muchnick was an American hero whose life was cut short, and we join his family and friends in mourning this tragedy," said Malloy. "Our prayers are with all of our armed forces who are serving this nation so bravely."

Loss deeply felt

The Marine's grandfather, Jerome Muchnick of Philadelphia, told the Associated Press on Wednesday that his grandson had served in Afghanistan and was thinking about returning to college after the Marines.

Jerome Muchnick says his grandson was a vibrant, loving man and he has been devastated by his death.

Whenever grandfather and grandson spoke, Jerome Muchnick recalled, "R.J. wouldn't hang up the phone without saying `I love you, grandpa.' And he was always texting me things like that, too."

First Selectman Gordon Joseloff, in a statement issued Wednesday, said the Marine's death was a sad day for Westport.

At Staples, Joseloff said, Muchnick "was well known as a popular football and lacrosse player, and was well liked by his friends, teachers and coaches.

"He is the second Staples graduate on active duty with the Marines to die in an accident in little more than three years, and our community once again is in shock," the first selectman said.

"Our hearts go out to the Muchnick family and friends. We deeply share their loss."

Justin Axel, Muchnick's lacrosse coach at Eastern Connecticut, told NBC Connecticut that Muchnick was someone who made a positive impression on everyone he met. "Roger was such an incredible kid. He played with so much passion and heart. And he was always smiling. That was the good thing about Roger, day in and day out he brought a smile to your face," Axel said.

ECSU plans a tribute to Muchnick and the lacrosse team will dedicate its next home game to his memory. "We'll be honoring him by wearing his number in our helmets for the rest of the season," Axel said.

"I thought the world of him and what he went on to do for our country was absolutely incredible. We really lost a great person in Roger and our hearts are deeply saddened with this event," Axel told the television station.

Staff writers Paul Schott and MariAn Gail Brown, and the Associated Press, contributed to this report.