Karen Bermudez-Rodriguez wanted to break up with her boyfriend. And she wanted him to give back her keys.

Bermudez-Rodriguez, a 26-year-old au pair who lived with a family in a New Jersey suburb, exchanged text messages with the boyfriend, Joseph Porter, on Saturday at about 1:30am Eastern time, according to court documents.

Less than five hours later, Porter used the keys Bermudez-Rodriguez had previously given him to enter the home of her employer, and stabbed him to death, according to the authorities.

He then bound Bermudez-Rodriguez's hands. When she fled, he chased her down the street with a knife.