(Video provided by Baltimore Police Department)

When the gunman in the surgical mask, sunglasses and latex gloves bursts into the Northeast Baltimore barber shop, nobody seems to flinch. 

Even when his gun jams when he points it at his unsuspecting victim, the gunman calmly takes time to fix it and carry out the execution. 

The chilling video capturing the moments before the murder of David Porter, 41, was released by Baltimore Police Department as they seek help solving the case, though the gunman's disguise all but ensures no one will identify him from the tape. 

But the video puts on full display the brazen and callous nature of the city's violence. 

Porter was the son of a Baltimore Police dispatcher, Alva Porter. She's worked for the department for more than 20 years. 

In an interview this week, Alva Porter said her son was getting his hair cut at the barber shop in the 4400 block of Frankford Ave. as he prepared to go to a reunion on the city's east side. He had spent two decades in prison stemming from a robbery killing committed when he was 23 years old, but had been released a few years ago and was trying to start a business, she said. 

Sources say that police believe Porter was a member of the Black Guerrilla Family gang, though it was not known if or how that may have factored into the shooting.

Anyone with information is asked to call homicide detectives at 410-396-2100.