Police are asking for help in finding a man involved in a string of armed robberies across Manhattan. 

A surveillance video shows the first robbery back in August. 

He is seen grabbing the victim as he is trying to get into his apartment. When the victim tries to run, the man pulls out a gun and then places him in a chokehold. After the victim loses consciousness, the individual stole one-thousand dollars and his cellphone. 

Four other incidents like this have taken place, the most recent on October 1st.