The wife and stepson of a Ku Klux Klan leader found fatally shot next to a river in eastern Missouri were charged in his death Monday.

Malissa Ann Ancona, 44, and her 24-year-old son, Paul Edward Jinkerson Jr, were charged with first-degree murder, tampering with physical evidence and abandonment of a corpse in the death of Frank Ancona. Both are jailed without bond.

A probable cause statement alleges that Ancona, 51, was fatally shot in his sleep on Thursday at his home in Leadwood, Missouri, about 70 miles south of St Louis.

St Francois County sheriff’s department detective Matt Wampler wrote that after the shooting, Ancona’s body was taken in Jinkerson’s vehicle to an area near Belgrade, Missouri, about 20 miles from Leadwood.

A family that was fishing in the Big river found the body on Saturday. An autopsy conducted on Sunday revealed that Ancona died of a gunshot to the head.

Jinkerson’s attorney, Eric Barnhart, said he didn’t believe his client was involved in the killing, but he declined to comment further. It wasn’t immediately clear if Malissa Ancona has an attorney.

Ancona called himself an imperial wizard with the Traditionalist American Knights of the Ku Klux Klan. A website for the group includes an image of Ancona in a white hood and robe standing in front of a burning cross. The website describes the group as a “White Patriotic Christian organization that bases its roots back to the Ku Klux Klan of the early 20th century”.

The Park Hills Daily Journal said investigators placed yellow police tape around Ancona’s home in Leadwood on Saturday, believing he was killed there. His safe had been broken into and the contents were removed. Several of Ancona’s guns were missing, police told the Daily Journal.

Washington County sheriff Zach Jacobsen said a US Forest Service employee found Ancona’s car on Thursday on a service road near Potosi, about 30 miles from where his body was eventually found. Ancona was reported missing Friday after his employer told Leadwood police that Ancona had not shown up for work for two days.

Investigators found evidence of a burn pile near Ancona’s abandoned vehicle, Jacobsen said.

Prior to the discovery of Ancona’s body, Malissa Ancona told police her husband had left the state on a delivery job. She said he planned to file for divorce when he returned.

Investigators said Malissa Ancona tried to destroy blood evidence and altered the crime scene in an effort to conceal the killing, the Daily Journal reported. Investigators said she was acting in concert with her son.