Here's What I Don't Get

I followed one of those links to a dumb, salacious news story today and I learned this:

The so-called "Preppie Killer," who served 15 years in prison for strangling a woman in Central Park, was arrested Monday on charges of selling drugs and resisting arrest.

Robert Chambers was released from prison on Valentine's Day 2003 after serving 15 years for the 1986 strangling of 18-year-old Jennifer Levin during a tryst in Central Park.

The undercover sting began after police received complaints alleging drug sales at Chambers' residence, where he lived with his girlfriend...

His girlfriend? He lived with his girlfriend?

Can somebody explain to me how a guy kills a woman "during a tryst" and then after he gets out of prison, finds a girlfriend to live with him?

Wouldn't you think that doing 15 years for murdering a woman would sort of take you out of the dating pool?