LINCOLN -- Five members of a Beason family killed in a "brutal homicide" earlier this week died from blunt force trauma, according to the autopsy results released Thursday.

Raymond "Rick" Gee, 46, his wife, Ruth Gee, 39, and three of their children, Justina Constant, 16, Dillen Constant, 14, and Austin Gee, 11, were found dead Monday afternoon in their house at 1571 2150th Ave., also known as Broadway.

"I am the one who found them," said William "Pudge" Koehler, Rick Gee's stepfather. "It is burned in the back of my eyeballs."

Koehler declined to comment further and said he was getting his first real sleep since the slayings.

Logan County Sheriff Steven Nichols would not comment Thursday on the type of object or weapon that may have been used to kill the family. However, The Pantagraph learned Thursday that authorities are looking for a sharp-edged tool and/or a cylinder-shaped object.

Nichols confirmed the fourth child found at the family's home also suffered from blunt force trauma. The child, 3-year-old Tabitha Gee, remains in critical but stable condition at a Peoria hospital.

As the investigation continued Thursday for the fourth day, Nichols announced he has formed a task force that includes officers from his department, Lincoln Police Department, the FBI, Illinois State Police and the Logan County state's attorney's office.

Nichols said "several dozen" officers are actively working the case.

So far the tip line, (217) 732-3000, established for the case had generated more than 100 leads for officers to check as of Thursday afternoon.

"We will continue to run down every lead or tip," Nichols said. "Our tactic is to keep going forward."

Police also have stopped a number of trucks in the hopes of finding the primer/gray, compact pickup truck that was seen before midnight Sunday in Beason, about 16 hours before the bodies were discovered.

Nichols said many of the tips they have received are for full-sized trucks, but that officers still are looking for a Chevrolet S-10 or Ford Ranger-type of pickup.

Tips also have been coming in to the Bloomington Police Department since the pickup truck description was released, said spokesman Duane Moss. All the leads are checked but so for Bloomington police have not found anything substantial.

Normal police and the McLean County Sheriff's Department said they have not received any tips.

Nichols would not comment on where in the house the five family members were found, saying he did not want to jeopardize the investigation.

He also would not comment on whether one person could have been responsible for the slaying.

State police crime scene investigators completed processing the house late Wednesday afternoon, and the last of the police officers left the family's home just before noon Thursday. Windows of the house were boarded up with plywood and the property still remains cordoned off with crime scene tape.

Nichols said the house will continue to be considered a crime scene.

Nichols said technicians have started the work of analyzing hundreds of items seized from the house as part of the investigation.

"Photographs, latent prints, blood specimens, DNA, all have to be analyzed and compared to known standards," Nichols said. "The forensic evidence in this case is significant, but will take time to complete."

Nichols would not elaborate on a possible timeline of events in the incident or a possible time of death.

The children and Rick Gee reportedly were last seen Sunday night, and the children were absent from school on Monday.

Nichols also would not comment on whether police found signs of forced entry to the house and whether robbery was a possible motive.

The Gees have been involved in several family-related court cases in Logan County Circuit Court. Nichols would not comment on whether those cases relate to the investigation.

Tony Sapochetti, Ryan Denham and Kevin Barlow contributed to this report.