By David Spunt

By David Spunt

PHILADELPHIA (CBS) — The boyfriend of a 22-year-old Port Richmond mother told Eyewitness News he had nothing to do with her death and wants to help police find her killer.

Authorities spent hours questioning Sean Sadowniczak after his girlfriend, Stephanie Dzikowski was found shot to death in their Port Richmond home. Authorities say she was killed just after 11 p.m. on Thursday, July 30th.

“I don’t understand why someone would do this. She was the best,” Sadowniczak told Eyewitness News in an exclusive interview.

He was one of the last people to see Dzikowski alive. The couple lived with their two-year-old daughter. Sadowniczak told Eyewitness News he wasn’t home when Dzikowski was killed. Authorities say the little girl was home when her mother was shot to death.

“I didn’t know what to think. I didn’t want to believe it,” he said.

Neighbors told police they heard a single gunshot. According to detectives, the front the door was open, giving the killer easy access. Homicide detectives are interested in surveillance video showing a possible suspect quickly run across the street.

Friday evening hundreds came out to remember Dzikowski, but Sadowniczak wasn’t there. He was in police custody, answering questions about his girlfriend’s murder. Police released him Saturday morning.

“I want to help them as much as they want to help me. They’re doing their job. Their doing as much as they can and that’s all that we want them to keep doing,” he said.

Sadowniczak has not been charged with any crime, and insists he had nothing to do with Dzikowski’s death. His focus is the couple’s two-year-old daughter, and helping police find Dzikowski’s killer.

“He could be walking by everyday giving me his condolences like everybody. It’s unreal. It’s crazy that someone would do this to me, let alone my little girl,” he said.

The City of Philadelphia is offering a $20,000 reward for a tip that leads to the arrest and conviction of Dzikowski’s killer.