Jeremy T. Lloyd already was in jail when he was formally charged with three counts of first-degree murder and one count of armed robbery in connection with the Sept 27, 2006, shooting death of on-duty Metra police officer Thomas Cook.

The 20-year-old Gary man was being held in the Cook County Jail on unrelated charges of attempted first-degree murder and aggravated discharge of a firearm stemming from a shooting in Harvey hours before Cook was shot, Cook County state attorney's office spokesman Andy Conklin said.

In that case, Lloyd and a co-defendant -- 21-year-old Harvey resident Jemetric Nicholson -- are accused of shooting at a former Harvey police officer at 3:22 a.m. near the intersection of 159th Street and Myrtle, according to court records.

The officer had responded to a call of shots fired, and when he arrived saw suspects drive away, Conklin said. A chase ensued, and as the suspects fled they shot at the officer before crashing into a tree, fleeing the scene and leaving their weapons behind, Conklin said.

Nicholson was being held in the Cook County Jail for his role in the incident when prosecutors charged him with additional crimes following the January 2007 state police raid of the Harvey Police Department.

As the result of the raid, Nicholson was charged in connection with the January 2005 murder of 20-year-old Aaron Thomas, of Calumet City, and with attempted murder for the February 2005 shooting of Martel Edwards and Maxine Dabbs in Harvey.

Nicholson also faces attempted murder charges stemming from separate incidents in November 2005 involving Ronald Simpson and his mother, Constance Simpson, and an unlawful use of a weapon charge.

The January 2007 raid was the result of an investigation that began in August 2006 after the Cook County state's attorney's office learned of reports about a gun that disappeared while in police possession and a host of unsolved homicides.

So far, the investigation yielded charges against at least seven people for crimes in and outside Harvey dating back to 2005.