Lt. Troy Klemstin's testimony Tuesday led off the case against Desmond Laster, who is charged with four counts of first-degree intentional homicide, as party to a crime, and arson in the grisly events of Feb. 26, 2010.
"It was surreal to me," the Milwaukee Journal Sentinel quoted Klemstin as saying in court.
In his opening statement, prosecutor Mark Williams called the case "a bad soap opera."
Rachel Thompson lived with her sons Torian Thompson-Carter, 4, Jaden Thompson-Carter, 3, and Maurice Visor Jr., 2 months. Also living there was Brittney Robertson, who was dating Laster but had previously conceived a child with Maurice Visor, father of Thompson's youngest boy.
Police say Robertson told Laster Thompson had money and a gun they could steal. Along with Anthony Barnes, they went to the home, where Robertson stabbed Thompson repeatedly, authorities allege.
Torian and Jaden were killed because they were witnesses, Williams said.
The trio took the baby, Maurice, to a motel and Robertson told friends what had happened to that point. Police posted her photo, believing she was in danger, but before she could be found, Barnes and Laster shot her, Williams said.
Barnes pleaded guilty and will testify against Laster.