NORTH MIAMI BEACH (CBS4) – North Miami Beach Police are piecing together an officer-involved shooting that left a mentally disabled man dead early Wednesday evening.

Officers tell CBS4′s Natalia Zea that a man carrying a rifle was seen walking through a neighborhood in the area of Northeast 155th Terrace and 14th Avenue.

Witnesses say the man even pointing the rifle at a dog at one point. Police say several neighbors called 911 to report the incident.

Police say when officers arrived, there was some sort of confrontation and one officer to open fire on the man.

But their investigation revealed that the “rifle” was in fact, a realistic looking toy. The injured man was taken to Jackson Memorial Hospital where he later died.

Family members say the man police killed is 56-year-old Ernest Vassell.

“They murdered him in cold blood for a toy gun!” cried Vassell’s older sister Claire Harding. “That’s no reason for you to kill somebody!”

Vassell’s sisters say they have never seen him with a toy gun, they believe he must have found it somewhere. They say he was mentally disabled after a brain injury as a child and that he has never been violent.

“They could tell him to drop the gun, they say they told him to drop it and he raised his hand, he probably raised his hand to hand them the gun because he is afraid of police,” said Harding.

The family is demanding answers and changes to the North Miami Beach Police Department.

“They should train these police officers better,” said Harding. “This is ridiculous, they just go around killing people for nothing.”

Police maintain the toy gun appeared to be a real rifle. One officer is on administrative leave while police and the state attorney’s office investigate.