Police say the body of an 18-year-old Kansas woman who had been missing for nearly a week was found in a farm field in rural Missouri and three are in custody in her murder.

Suspects Joseph Mattox, 21, Gerald Calbeck, 18, and Dustin Hilt, 18, were arrested late Monday in the death of Keighley Ann Alyea of Overland Park, FOX4KC.com reported.

Alyea disappeared about midnight Sept. 29; her body was found about 9:30 p.m. Monday.

An autopsy was being conducted Tuesday at the Jackson County medical examiner's office in Kansas City, Mo.

Friends told FOX4KC.com that Hilt had dated Alyea for a couple of years and they were not surprised he had been named a suspect.

Both had tattoos of each other's names on their bodies, but the couple's relationship was tumultuous, the friends said.

"I don't know how many times she's called me because Dustin had hit her, or her and Dustin had gotten into a huge argument and it got a little confrontational," ex-boyfriend Jaymes Beebe told the station. "It was not a good relationship."

Beebe said Hilt had "gotten her hooked on drugs really bad," and she "got clean when she stopped talking to him."

Police had been concerned that Alyea was in danger after she intervened on Sept. 28 in a violent argument between Beebe and his sister, Jessika.

Jessika Beebe had slept at Alyea's house after the fight — but when Jessika woke up the next morning, Alyea was gone, the murdered teen's mother Kelley Bastel told FOX4KC.com.

Jaymes Beebe has been cleared of any wrongdoing after police questioned him over the weekend, the station reported. Mattox, Calbeck and Hilt were then arrested Monday night.

Alyea's family has established a memorial fund in her name. Donations can be made at any Commerce Bank.

Click here for more on this story from FOX4KC.com.

The Associated Press contributed to this report.