Father-of-ten Robert Godwin Sr (pictured), 74, was shot dead in an apparently random attack as he collected aluminium cans in Cleveland, Ohio, at the weekend.
Police officers across five states are now trying to find 37 year old youth counsellor Steve Stephen who is wanted on a charge of aggravated murder.
Speaking to journalists, one of Mr Godwin's daughters -she was not named - said of the suspected killer: "I just want him to know that God loves him. We love him. Yes, we're hurt but we have to forgive him."
A video capturing his shooting was on Facebook for approximately three hours before it was removed, while the social website also eventually took down Stephens's Facebook page.
The company said: "This is a horrific crime and we do not allow this kind of content on Facebook.
"We work hard to keep a safe environment on Facebook, and are in touch with law enforcement in emergencies when there are direct threats to physical safety."
Police say they have searched dozens of locations in Cleveland as part of their search for Mr Stephen, while they have been in contact with him via mobile phone.
Godwin claimed he had killed more than a dozen people, however, officers say Mr Godwin is the only victim so far being linked to Stephen.
The motive for the shooting was not clear in the poor quality footage but it allegedly captures Mr Stephens told Mr Godwin a woman's name, adding "She's the reason that this is about to happen to you."
Mr Godwin did not appear to know the woman's name.
A makeshift memorial sits at the place of Sunday's shooting.