Atlanta Police detectives say they are working with authorities in Gwinnett County to determine whether a murder-suicide in Norcross is tied to an earlier murder. Jermaine Roby is believed to have killed his 55 year old mother Josephine Roby-Skinner and his 10 year old sister Jasmyn Skinner and to have then taken his own life. Their bodies were found in a home in Norcross Friday. The father arrived home and found his family dead according to police. Reports indicate that the 27 year old Roby is also considered a person of interest in the death of a man in Atlanta earlier in the day. Atlanta police say 40 year old Quincy King was found shot to death inside a home on Northside Circle.