Thomas Alan Cook was a 43-year-old Metra Police officer working a surveillance shift near the Metra Electric Line stop at 147th and Clinton in Harvey, Illinois, on September 27, 2006. While seated in his marked patrol car across from the station, someone walked up to the driver’s side and opened fire, striking him in the head and stealing his service weapon before fleeing. He was the first Metra Police officer killed in the line of duty.

Investigators later developed suspects. By January 2009 one of two suspects, described in court records as a lookout, was charged and eventually pleaded guilty in October 2010 to murder for his role in the ambush; he also admitted an attempted murder earlier that same day. On November 10, 2010, prosecutors charged 23-year-old Jemetric Nicholson of Harvey as the gunman, alleging the pair targeted the officer to steal his gun as a replacement for a weapon lost in the earlier shootout. A first trial ended in a mistrial, but in January 2016 a jury found Nicholson guilty of first-degree murder and in March 2016 a judge sentenced him to natural life in prison with no possibility of parole, to run consecutively to other terms.

The case record traces a sudden, planned ambush: an officer alone in his car on a chilly September night was executed in a scheme to take his weapon.