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CASS COUNTY, Mo. — For nine long and grueling hours, more than 100 investigators from the Kansas City Police Department, the Cass County Sheriff’s Office, the FBI and several other metro area law enforcement agencies searched a thick, muddy wooded area on Thursday.

“The FBI’s crime scene team is first going to grid the area into squares to make it easier for the searchers to see. We have a rather long area that is very difficult to see,” said Captain Kevin Tieman with the Cass County Sheriff’s Office.

High in the air with a drone, on the ground, crawling around on their hands and knees, and shoulder to shoulder in the snake-infested woods, the searchers scoured almost three acres of rugged terrain near East 233rd and Y Highway Thursday afternoon.

Their mission?

Find anything that could lead them to the person who killed 21-year-old Jessica Runions who had been missing for seven months before investigators confirmed Wednesday a skull, a mushroom hunter found earlier this week, belonged to the missing woman.

The searchers also carefully examined “anything human-related,” said Cpt. Kevin Tieman.

“We want to find anything that we think could help solve Runions’ murder mystery or help identify a second set of human remains found at the same site this week,” added Cpt. Tieman.

“We would’ve loved to have found her alive and well, but unfortunately, that’s not the case. Our thoughts and prayers go out to the Runions family,” said Captain Stacey Graves with the KCPD.

For hours, the searchers tackled the tough terrain and put down bright, orange, miniature flags, marking off anything they thought could be “evidence” in connection with both crimes.

By late afternoon as the search began to wind down, Cpt. Tieman updated then news media.

“We did identify several pieces of evidence. I’m not ready to tell you if they’re human remains or something else, but we are recovering evidence and things that we believe will help us possibly identify the second person and help with the ongoing homicide investigation,” Cpt. Tieman said.

Meanwhile, investigators desperately want to know whether the second set of human bones belonged to Kara Kopetsky, who has been missing for 10 years now.

“Investigators are working tirelessly to identify those second bones, ” said Captain Stacey Graves.

On Friday a specialized team of crime scene technicians and investigators “who specialize in the recovery of human remains will be back at the Cass County site at 8:30 in the morning,” said Cpt. Tieman.