Miami Herald -- A decorated young Marine from Southwest Miami-Dade was killed in action Sunday in Iraq, the military announced Monday.

Lance Cpl. Rene Martinez, 20, died during a combat operation against enemy forces in Iraq's al Anbar province.

Martinez, a mortarman, joined the armed forces in July 2004 and was deployed to Iraq about three months ago.

His unit, based in Camp Lejeune, N.C., has spent its tour of duty training and working with Iraqi security forces, said 1st Lt. Barry Edwards, a 2nd Marine Division spokesman.

''In doing so, they were denying insurgent strongholds in and around several Iraqi cities,'' Edwards said.

Martinez, a graduate of Miami Sunset Senior High, wanted to be a Marine since he was a little boy, his sister Maria ''Gaby'' Martinez said.

Martinez, 19, last heard from her big brother on Sept. 13. He was a dedicated service member, but when Rene Martinez spoke with his family, he avoided talking about his experiences in Iraq, his sister said.

Instead, they talked about happier times and future plans. The siblings planned to move back to Miami around the same time, when Gaby Martinez graduates from college in Georgia and when her brother got out of the service.

''He was determined to finish his four years with a good record, then he wanted to come back home and study accounting,'' Gaby Martinez said. ``He had a good heart.''

Rene Martinez had been assigned to the 2nd Marine Division since January 2005. In that time, he earned medals for combat action, overseas deployment and global terrorism service.

''He was a fairly well decorated Marine for his age,'' Edwards said.

Funeral arrangements for Martinez are being planned. His unit will organized a memorial for him in Iraq, Edwards said.

Martinez was the second South Florida service member killed in Iraq this month. On Sept. 10, Army Spc. Alexander Jordan, 31, of Palmetto Bay, died after being attacked by enemy fire in Baghdad.

At least 119 service members from Florida have been killed since the U.S.-led invasion of Iraq.