Pfc. Deryk L. Hallal looks serious in his Marine Corps photo. Too serious, his mother says — and not at all like the man who often performed impressions of John Kerry, Ross Perot and the commander in chief he admired, George W. Bush.

“He was a big jokester,” Pam Hallal said. “He could light up the room.”

She remembered the humorous side of her son after he died April 5 in Iraq, less than two months after leaving home. The 24-year-old North Central High School graduate was among more than a dozen Marines killed in recent days and was the second Hoosier to die in Iraq this week.

Hallal was shot and killed in al-Anbar province in western...