ELGIN, Ill. (CBS) — He was serving his second tour in Afghanistan, when a U.S. Marine from Elgin was killed in combat this week.

Cpl. Alex Martinez died Thursday in the Helmand province of Afghanistan.

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CBS 2’s Derrick Blakley reports Martinez’s family is now mourning the loss of a quiet leader.

From his earliest high school years, Martinez, 21, knew he wanted to join the marines.

His cousin, Miriam Martinez, said “he wanted to do something besides just working. He wanted to help people, but in a way that he’s helping himself. He was a very strong, positive person – that if he commits himself to doing something, he’s willing to do it.”

Cpl. Martinez’s high school teachers and friends called him quiet, smart, and hardworking. He took summer classes to graduate early from Larkin High School in Elgin.

He signed up with the Marines as soon as he could, on his 18th birthday in December 2008.

David Pizarro grew up across the street from Martinez.

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“They would always have, like, little parties for him when he came home. And, yeah, he would always come dressed up, in uniform,” Pizarro said.

About the same time he joined the Marines, Martinez married his fiancée, Juliana. She saw her husband when he returned to the U.S. last month, just before his deployment to Afghanistan for the second time.

“It’s unbelievable. Just two weeks ago he was happy, you know, with his wife and everything. And now, he’s gone,” Miriam Martinez said.

A small American flag adorned the lawn in front of Cpl. Martinez’s home in Elgin on Saturday. The house sat empty.

His mother and stepfather flew to Dover Air Force Base in Delaware on Saturday, to meet the arrival of their son’s remains from Afghanistan.

Sunday morning, Martinez’s family friends will gather at Veterans Memorial Park in Elgin, to remember Martinez’s life of service, and the sacrifice he made for his country.

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Martinez was assigned to the 1st Combat Engineer Battalion of 1st Marine Division at Camp Pendleton, California.