Timothy Herring, the 24-year-old man who killed a Chicago police detective and a former Chicago Housing Authority officer in November of 2010, was sentenced to life in prison without parole Friday.

Herring was found guilty in May for the murders of Chicago Police detective Michael Flisk, and former CHA officer Stephen Peters. Flisk had been dispatched to investigate a burglary of stereo equipment from Peters’ mother’s garage. Evidence showed that Herring, who had committed the burglary, shot both in the head, then shot them a second time as they lay dying before him.

"The murder of my father has greatly affected my life," said Flisk’s daughter Margaret, who described holding her father’s lifeless hand, still covered in fingerprint dust. "He was killed doing what he loved."

Peters’ wife D’Jana spoke directly to her husband’s killer.

"My heart was torn to pieces when you killed my husband," she said. "Do you know what it’s like to have someone you love executed in cold blood?"

Peters owned a red Mustang that was parked inside a garage in the 8100 block of South Burnham Avenue and had called police when he discovered stereo equipment and other parts had been taken from the vehicle. Flisk was dispatched to investigate and process the crime scene.

Prosecutors said Herring killed the two because he knew fingerprints on the car would link him to the burglary.

"You look at the life of Timothy Herring, and you look at a life of crime," said prosecutor Thomas Maloney, who called Herring "horrifying…ghastly…a cold-blooded executioner."

The defense tried to paint Herring as the victim of a broken system, an individual who had been treated as an adult even when he committed crimes as a teenager. But the argument fell on deaf ears.

As she sentenced him to life without parole, an outraged Judge Mary Margaret Brosnahan wondered aloud, "So cold, so calculating, you have to wonder why?"

"You made the decision that your concerns were more important than the lives of two human beings," she said. "Down they went, and dead they were."

After court, Cook County State’s Attorney Anita Alvarez rejected the defense argument that Herring had been a victim of the very system which put him on trial.

"This particular case, the murder of two individuals, it is a very adult crime and he clearly knew what he was doing when he committed these crimes," she said. "This is another example of the senseless use of guns out there on the street by violent people."

Herring had previously been convicted of armed robbery and sentenced to six years in prison, but was released on parole a little more than two months before Flisk and Peters were killed. Prosecutors established that he had recently attended a federal program, informing him of the stiff jail sentence he would receive if he was arrested for another crime.