In a column for Time
in which he honors his late wife, Oswalt also shared other details about her life that weren't as well known.
McNamara died unexpectedly in her sleep April 21 at the couple's Los Angeles home.
In a nod to his wife's career as a true crime writer, Oswalt began his piece by writing "Michelle Eileen McNamara entered the world on April 14, 1970. On April 14, 2016 she turned 46. One week later she was gone."
"That's the kind of opening Michelle would have written," he wrote. "She'd have done it better. Added one perfect adjective or geographical shading to pull you in."
McNamara was well known for her blog TrueCrimeDiary.com. At the time of her death, she was writing a book about the Golden State Killer, according to her husband.
Oswalt also described other endeavors his wife pursued.
"Her life also involved social work in Belfast and Oakland, and screenwriting in Los Angeles, and teaching creative writing at Minnesota State, and motherhood and marriage and glorious, lost years on the outskirts of the early 90s Chicago music scene, where she also worked for a young Michelle Obama," he wrote. "One day Michelle Obama's husband came into the office to speak to the staff. He was impressive and funny. Another encounter, another memory in a life spent fascinated with people and relationships and the unknown."
The actor also wrote of his and McNamara's seven-year-old daughter, Alice. He told People magazine
he is preserving his wife's memory for their child.
His wife "approached motherhood with the same bemused optimism she met everything else with," Oswalt said. "She loved being a mother."