Manhunt Monday: Who killed Samuel Johnson?

MEMPHIS, Tenn. — Police are looking for answers to a case that's been cold for four years.

Now a heartbroken father is making a plea for help.

Reginald Johnson knows the hurt and pain of losing a child to violence.

"I`m not ashamed to say it, it`s been the worst time of my life," the father said.

Memphis Police say four years ago, his son Samuel Johnson was walking down Glenalp near Derbyshire when someone driving a dark colored car pulled up and opened fire.

The victim's father believes his son was set up to be killed.

He says the 21-year-old got a call from two people inviting him to a Halloween party at a gym..

"He left here walking to the gym, and about thirty or forty minutes later people were knocking on the door saying Sam was laying in the street," Johnson said.

Home surveillance video shows the victim walking down the street seconds before he was killed.

His father never though when he saw his son walk out of the house that evening it would be the last time he would see him alive.

"I take medicine at night so that I can go to sleep," Johnson said. "Nobody knows the pain that this stuff causes to a family."

It's pain that never seems to get any better.

Homicide detectives say this isn't the first time Samuel Johnson was targeted.

Officers say he was shot in the back weeks earlier.

"There are several different little neighborhood gangs in this area that could have had some involvement in this," an officer said. "This will happen again and again if we don't get some of these killers off the street."

If you know who killed 21-year-old Samuel Johnson call Memphis Police at (901)-528-CASH. All calls are confidential.