The bones of Mark Koster were discovered in the basement of his former house in November 2012.
The bones of Mark Koster were discovered in the basement of his former house in November 2012.
March 26, 2014

A transient man who lived for about a month with Mark Koster, 58, in his Sac City house in 2009 allegedly struck Koster in the head and choked him to death with a wooden baseball bat and buried Koster's body in the basement of the house, according to court documents.

John David Green, 54, was arrested in Florida after he allegedly admitted to killing Koster in an interview with investigators on Tuesday. He faces a first-degree murder charge, which is punishable by up to life in prison.

Investigators had sought Green for months after Koster's bones were discovered in November 2012 inside the house at 610 N. Fifth St.

Green told law officers on Tuesday that Koster attacked him with the baseball bat on June 5, 2009, and struck Green in the shoulder, court documents show. Green took the bat from Koster and struck Koster in the head, which caused Koster to bleed and fall to the floor on his back. Green then sat atop Koster and choked and crushed Koster's throat with the bat for about two minutes.

Green admitted he dragged Koster's body to the basement, cleaned the alleged crime scene of evidence and left a note that made it appear Koster had left Sac City indefinitely.

Green stayed at the house for a few days and then went to Mississippi to visit his father. It's unclear how Green and Koster had met and what led to the fight.

Koster's family reported him missing in 2010 after Koster had stopped paying his utility bills, according to court records.

Investigators who searched the house found Koster's clothing and other possessions undisturbed - including his pipe and tobacco, the records show. Koster's vehicle was in the house's garage.

They found no trace of the man "despite extensive efforts to locate the missing person by the Sac County Sheriff's Office, the Sac City Police Department, the Division of Criminal Investigation and other law enforcement agencies," Koster's brother Daniel Koster wrote to a judge in 2011. A jury later determined that Mark Koster "has suffered death by accidental or other violent means," court records show, and a Carroll man, Lesly Gehlsen, 73, later bought the house for $5,000.

Gehlsen was cleaning the house in November 2012 when he discovered Koster's bones buried in the basement.

"It was strange," Gehlsen told the Daily Times Herald at the time but declined to talk further.

A state medical examiner found that Koster's neck bone and cartilage had been fractured, court documents show.

Gehlsen still owns the house, according to county property records.

An initial court hearing for Green has not been set. It's unclear when he will be extradited to Iowa.

Green was not charged with any other crime, nor cited for a traffic violation, in the time that he lived with Koster, according to online court records.

Green had been most recently living in Orange Park, Fla., a suburb of Jacksonville in the northeast part of the state about 1,300 miles from Sac City.