Sounds like an affair gone bad ...She wanted to end it , he didn't . He wanted more sex and she wouldn't give so he sexually assaulted her . Guess he figured he wasn't going to get away lightly this time and ended it all rather than go to prison .
Perp (Boyfriend/Convicted Rapist/Murderer):
1) Was the perp a registered sex offender in the State of Georgia (the crime and sentence having been served overseas)?
2) Did the girlfriend know of the perp's past?
3) Did the parents of the murder victim know the past of the perp?
It would be instructive to know these. If in the case of #1, he was NOT on some kind of Georgia state sex offender list, then this calls up all kinds of questions, i.e. Americans overseas after horendous crimes are committed, but no communication from the foreign authorities or US military to the states.