TECUMSEH, Kan. (WIBW) – Shawnee Heights dive teams pulled a gun from Lake Shawnee late Monday afternoon.

It's believed to be the weapon that was used early Sunday morning to shoot and kill 51-year old Gerald Eberhardt in his Tecumseh home.

The Shawnee County Sheriff's Office reported Monday that a fourth person was accused in the killing. They say 20-year old Derrick Haase was taken into custody shortly after the incident early Sunday morning.

The Shawnee County District Attorney's Office filed formal charges Monday against Haase and the three others who were arrested in Eberhardt's death.

Haase, 43-year-old Michelle Eberhardt, 19-year-old Scott Mosher and 21-year-old Stephanie Menard are charged with premeditated first degree murder and conspiracy to commit premeditated murder.

Michelle Eberhardt is the victim's wife. Mosher is the victim's stepson. Menard is believed to be Mosher's girlfriend. Authorities say Mosher and Haase are associates and are involved with gangs.

Eberhardt was shot and killed in his Tecumseh home, 2538 Shawnee Heights Road, early Sunday morning. The Shawnee County Sheriff's Office says Michelle Eberhardt called 911 shortly after the shooting happened.

Authorities say the suspects are cooperating with investigators. They say information from the suspects is what led them to discover the weapon in Lake Shawnee.

The Sheriff's Office says authorities had been called to the Eberhardt home 14 times this year. They say three of those calls were alarms. They also had five calls for domestic incidents and a couple of burglary reports.

13 News has learned that Michelle Eberhardt filed a temporary restraining order from Gerald Eberhardt in August 2005. Public records also indicate that one of them filed for divorce that month as well.

13 News has also been told that Gerald Eberhardt is the owner of Wizz By Auto Sales in Topeka and Michelle Eberhardt ran a bookstore out of her home.

Anyone with information is asked to call Detective Thompson at (785) 368-2242.