They also described him as a young man with an interest in politics who liked to party. Edward Perkovic, who said he first met Poplawski in daycare, told the Pittsburgh Post-Gazette his friend was a "good kid."
Aaron Vires, 23, said he sometimes worked with Poplawski and Perkovic on a radio show they broadcast on the Internet that focused on "politics, girls and life." Vires, who is black, said he and Poplawski had "spirited debates" about Obama but said his friend is not a racist.
Poplawski grew up in Pittsburgh with his mother and grandmother. Friends said his father "was not in the picture."
He was expelled from North Catholic High School and received a dishonorable discharge from the Marines, something friends said he engineered because he wanted to return to his girlfriend. He moved to Florida for a while, working as a glazier there.
But Poplawski appears to have some radical right views, the newspaper said. Perkovic said he had talked about "Zionist propaganda."