Police say Ramarley Graham did not have a weapon. He was killed within a few feet of his grandmother.
Internal Affairs is investigating the use of deadly force.
Graham's parents spent Saturday with community leaders at a service in Harlem led by the Reverend Al Sharpton.
"This is wrong and we want justice," Rev. Sharpton said.
Graham's parents also met with police and the D.A. to address their concerns with the case.
Protesters held a rally on Third Avenue in the Bronx late Saturday afternoon.
The 30-year-old officer who fired the deadly shot is a 3-year veteran, but his identity is not being released. NYPD Commissioner Ray Kelly says he has been placed on restricted duty.
Exclusive surveillance video shows some of the final moments of 18-year-old Ramarley Graham's life.
He's shown running along 229th Street towards his house, with an officer on foot, walking, about 20 seconds behind him, and then patrol cars with their lights flashing, speeding past.
But it is what happened once inside of Graham's home that has his family heartbroken and sickened.
"They come in and kill him in his bathroom cold blooded murder, we call that manslaughter," said Delmar Scott, Graham's brother.
Police Commissioner Ray Kelly says it started when officers investigating possible narcotics sales at a nearby bodega, saw Graham, believed he had a gun, and then followed him around the corner, up his street and into his house on East 229th Street.
He says they then confronted the teen in the bathroom.
The officer reportedly called out a warning before firing that fatal shot into his chest.
"The partner also reported hearing the shooting officer as he stood at the bathroom door yell, 'Show me your hands! Show me your hands!' And then 'gun, gun,'" Kelly said.
Police radio transmissions came next.
"Shots fired 749 229 Street."
"Get EMS here central, I got a male shot."
"Be advised there's plain clothes at the scene."
"We're on the second floor, we want this house frozen, nobody else in here, nobody out," the transmissions said.
But, with no gun found at the scene, neighbors are now the ones screaming out murderer! Murderer!
Friends and family are saying that this is another Sean Bell case.
"They think the badge they carry on their chest is a license to kill people," Scott said.
"I think they shoot first and ask questions later," a neighbor said.
With internal affairs now asking plenty of questions, it is still a process that's not quick enough for grieving friends and tearful family members who are now impatiently waiting for answers.
Investigators believe Graham ran because he had marijuana and was rushing home to flush it down the toilet.
According to police sources, Graham had eight prior arrests dating back to 2008. Four of those arrests are sealed, but other charges include burglary, possession of stolen property, drug possession, resisting arrest, disorderly conduct and robbery.
Get Eyewitness News Delivered