After graduating from high school in 2007, Sean Osterman knew he was headed to the military, but took his time researching which branch might be best for him.

He chose the Marines, and it was not just because his father was a colonel.

Last week, during his second tour in Afghanistan, Osterman, 21, of Princeton, Minn., was mortally wounded while leading his platoon in Helmand Province in southern Afghanistan. He was evacuated to Kandahar and then flown to Landstuhl Medical Center at Ramstein Air Force Base in Germany, where he died Saturday.

He was assigned to the 2nd Reconnaissance Battalion, 2nd Marine Division, II Marine Expeditionary Force, Camp Lejeune, N.C., and was part of what is known as a recon unit, which often conducts surveillance and intelligence gathering beyond the front lines. His unit had been in Afghanistan since about Thanksgiving.

According to a statement released by his family, he was born in La Crosse, Wis., and lived near there until age 9. The family moved to Princeton, where he attended Cambridge Elementary School, Cambridge Middle School and graduated from Technical High School in St. Cloud in 2007. He joined the Marine Corps at age 17 on the Delayed Entry Program and went on active duty after graduation. He had completed one tour in Afghanistan before his current deployment.

Although he had found his time in the Marines rewarding, he had indicated to friends and relatives that he would be leaving the military after completing his service and planned to attend college. During basic training and afterward, if fellow Marines had questions about the service, he would often send his father letters seeking advice for his colleagues.

His father, Marine Reserve Col. Anthony Osterman, was at one time responsible for training and equipping and manning the Afghan security forces, according to an earlier release from the U.S. military. He has since retired from the military.

His mother, Kelly Hugo, a guidance counselor at North Junior High School in St. Cloud, traveled to Germany to be with her son before he died and returned to Delaware with his body Monday night.

In addition to his parents, he is survived by sisters Katie and Olya Osterman, both of Virginia Beach, Va., and two other siblings, Elijah and Sarah Pruka, both of Princeton. Funeral services are planned at the Fort Myer Chapel with interment at Arlington Cemetery. A local memorial service will be planned in the near future.

Mark Brunswick • 612-673-4434