Police have used DNA evidence to build a profile of the man they they believe raped and murdered a Google executive in Massachusetts while she was out jogging last summer.
The partially burned body of Vanessa Marcotte, 27, was found in a wooded area in Princeton, half a mile from her mom's home, on August 7 last year.
Now, six months on, police say a DNA breakthrough has revealed the appearance of someone who was on the scene - and they hope that it will help them crack the case.
Officials are seeking a Hispanic man of average height and an athletic build, Worcester County district attorney Joseph D Early Jr said in a press conference.
He said the man is around 30 years old and had a shaved head or short hair on the day of the murder
He also likely had scratches or cuts on his face, neck, hands and arms that day, police said.
They added that they believe him to be the same man seen driving a dark coloured SUV in the area around the time that the young jogger was killed.
The public is warned not to confront anyone suspected of being the killer, as he is to be considered dangerous. Instead, they should contact police.
Police have not revealed how they acquired the DNA, saying only that they got it during the course of their investigation.
It is also not clear exactly how the DNA was used to build the profile.
Marcotte vanished on an afternoon run while on a visit to the home her mum Rosanna, lived in off Brooks Station Road. Marcotte lived in New York.
Her naked body was found at around 8.20pm in woodlands near the home. She had been sexually assaulted, and her hands, feet and part of her head were burned.
It's believed she was killed some time between 1pm, when she left her mom's home, and 4pm.