The National Transportation Safety Board says it suspects a natural gas leak sparked an explosion and fire that destroyed a home in a Crestwood cul-de-sac and killed Robert Conrad Milham, Jr., the home’s owner.

In its preliminary report, the NTSB said testing the day after the June 12 explosion found the presence of natural gas near the home’s foundation.

The board said the home that was leveled, 14105 S. Kenneth Court, had also been consuming more natural gas than neighboring homes of similar size and age.

Crestwood fire officials said at the time a natural gas leak was suspected.

After the explosion and fire, first-responders found Milham, 76, dead in the home’s basement.

The Cook County medical examiner’s office is still working to determine the cause of death.

Neighbors described the sound of the explosion as a bomb detonating, which was followed by a fire that started small but quickly grew in size.

With homes tightly spaced on the cul-de-sac, neighbors said that everyone saw Milham, who was a military veteran and had lost his wife a few years ago.

The NTSB said that, over the past year, the home had used more natural gas than neighboring homes did, and finding out why is part of the ongoing investigation.

In the report, the board said it continues to examine physical evidence recovered at the scene.

Other residents told the Daily Southtown the day after the explosion that residents had, in the past, smelled what they thought was natural gas and reported it to Nicor Gas.

The NTSB said part of the continuing investigation is the utility’s response to residents’ past reports of a natural gas odor.

A spokeswoman for Nicor said, in an email Thursday, that it can’t comment on the ongoing investigation but is “working closely and cooperating fully with the NTSB.”

The NTSB said there is a 1.25-inch steel gas main that runs in front of the home that was destroyed and that the main was installed in 1988.

The report said that a half-inch polyethylene service line, installed in 1992, ran from the main line to the home.