Chicago Police so badly mishandled the 2015 shooting death of off-duty police Sgt. Donald Markham that they violated Illinois law and prevented a legitimate investigation into suspicions that the sergeant may have been murdered by his wife and fellow Chicago Police Officer Dina Markham, according to an investigation released Wednesday by the city’s inspector general.

Markham was killed by a gunshot wound to the head and his death was ruled a suicide.

But in his report, Chicago’s Inspector General Joe Ferguson finds that the police officials in charge of the investigation were so quick to conclude that Markham died by suicide they prevented a proper investigation from ever taking place. IG investigators also found that the officers violated Illinois law by moving Markham’s body after his death.

Markham was pronounced dead in his home at 3:34 a.m. on Sept. 2, 2015, but Chicago police waited nearly two hours to notify the Cook County medical examiner of his death. Police also transported Markham to the county morgue, rather than waiting for a medical examiner investigator to come out to the scene, as required by policy and Illinois law.

According to the IG report, because detectives immediately assumed the death was a suicide, they did not do any of the things that would normally be part of a death investigation.

Detectives did not talk to neighbors, who later told the IG they heard the couple arguing shortly before the death, even though Dina Markham claimed she was not home when her husband died. They did not test Dina Markham’s hands for gunshot residue. They did not interview paramedics who told the IG they had suspicions the body had been moved before they got there. They did not contact Donald Markham’s siblings, who told the IG that Dina Markham had repeatedly threatened to kill her husband and make it look like a suicide.

Dina Markham died in 2017.

According to the inspector general’s report, the lieutenant in charge resigned before the investigation was completed. A detective and a sergeant were each given five-day suspensions.

In a statement, police spokesman Anthony Guglielmi pointed to the fact that the Federal Bureau of Investigations did investigate the handling of Markham’s death but “never filed any criminal charges or recommended any administrative sanctions” against the officers. Guglielmi said based on that, and discipline for similar rule violations, the five-day suspensions were fair “and in accordance with past practices.”

Patrick Smith is a reporter on WBEZ’s Criminal Justice Desk. Follow him @pksmid. Email him at psmith@wbez.org.