Robert Plight's alleged killer caught on camera

This man was caught on camera inside a BP gas station Saturday, moments before Robert Plight was gunned down outside.

The man wanted in a fatal shooting was caught on camera as he casually walked into a gas station on Benning Road Saturday, moments before Robert Plight, a 31-year-old father of five, was gunned down outside.

Plight's death has left all who knew him in shock, and his father is at a loss for words.

“I feel like this, if you never lost one you wouldn’t want to,” says Matthew Plight. “It is a feeling that is hard to explain.”

The grieving father saw images of the man police want to talk to. He saw the instant before and after the final moment of his son's life.

“It was terrifying,” he says.

"The video is very clear so we are confident if someone knows this person or sees him they will be able to identify him for us," Cmrd. George Kucik says.

Plight’s family says their son was going to the rescue of his two teenage brothers and two young nephews after a man tried to rob them and threatened to kill one of his children. The suspect allegedly told Plight's 12-year-old nephew, “You ready to die for your money?” When the group of boys alerted the family of the attack, Plight walked down to the gas station and was fatally shot. His mother says he didn’t have a chance to ask the person what happened, but calls her son a hero.

“He was doing the right thing and now he is gone,” Shirley Plight says.

"We are just trying to get everything together, keep everyone strong," his father says.

A reward of up to $25,000 is offered for information that leads to an arrest and conviction.

Video: Metropolitan Police Department