By AP/KWMU

Jefferson City, MO – Witnesses to Tuesday night's shooting at a Jefferson City factory say Jonathon Russell calmly smoked a cigarette and drank a soda before walking to his workstation and firing at co-workers.

Three workers died; Johnson then later killed himself. Jefferson city Police Capt. Jim Johnsen suggested a possible motive Wednesday: "I understand they work on some merit or demerit system and he may have been approaching the point where demerits would require his being laid off."

Police say he was on probation for excessive absences at the Modine Manufacturing Plant.

Five other employees were wounded in the shooting. The plant is closed for the rest of the week.

Besides the workplace problems, police say the 25-year-old faced the possible break-up of a romantic relationship.

Two of Russell's co-workers died along the manufacturing line and a supervisor died on the way to a hospital. Russell killed himself outside police headquarters after officers confronted him there.

The gun that police say was used in the shooting once belonged to a Missouri State Highway Patrol trooper. The gun is stamped with the patrol's emblem and the letters MSHP.

The .40-caliber Glock semiautomatic pistol was apparently legally sold to a gun dealer in Jefferson City, who in turn sold it last month to Russell.

Officials say a check on Russell showed he had no criminal record, so there was no reason not to issue the permit for him to buy the gun.

The Modine Manufacturing plant, meanwhile, will stay closed at least through the rest of the week. Modine is a Racine, Wis.-based company; it makes air and oil filters for various engines. The Jefferson City operation is one of its four plants in Missouri; the others being at Camdenton, Joplin and Trenton.

The Jefferson City plant was a work force of 270. Officials say there were 140 employees inside the plant at the time of Tuesday night's shootings.

Send questions and comments about this story to feedback@stlpublicradio.org.