HALLOWELL, Maine — Casey Andrew Chapman, the Army specialist from Chelsea, Maine, who was found dead last Wednesday in his vehicle at Fort Hood in Texas, was remembered as a “free spirit” with a “wonderful smile” by a former high school teacher Monday.

The Army continues to investigate Chapman’s death, the cause of which remained unknown as of Monday.

Chapman joined the Army eight months after graduating from Hall-Dale High School in Hallowell. His friends and teachers remember him as a young man with long hair and a big smile.

“My biggest memory of Casey is just his wonderful smile and his bright eyes. He was a real free spirit,” Chapman’s homeroom teacher in high school, Deb Large, said.

“(Casey) would do what he felt like,” she said. “But he was always kind to people. The students remember him as being just really funny and kind and genuine. And he really loved to skateboard. I mean, he skateboarded non-stop. And he was really, really good at it.”

Large said her youngest son, Tyler, was one of Chapman’s best friends.

Students and staff at Hall-Dale High School reacted with shock and sadness to the news of Chapman’s death, Large said.

“It’s shocking to know there was a student walking around here and friends with people and in the building and that he’s no longer — no longer with us,” she said.

In high school, Chapman learned to work on cars. In the Army, he was an artillery mechanic.

Chapman earned several awards and decorations serving overseas, including the Global War on Terrorism Medal.

“I think it’s hard for anyone to make sense of it,” Large said. “And there are other students here who have siblings in the military right now. I think it’s also really hard for them.”

A Fort Hood spokesman said the circumstances surrounding Chapman’s death are still under investigation. Casey’s father told CBS 13 that family members are still waiting for word on what happened.

There are more than 50,000 people stationed at Fort Hood. Chapman is the fifth Fort Hood soldier to die on or near the base in the last two months. Three others were found dead inside their off-base homes, and a fourth was found shot to death. An Army spokesman said all five deaths are under investigation.