Expert: Arson investigators did "heroic job"

Arson investigators work the scene at Richmond Hill.
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An expert who has helped send arsonists to prison says the case against the three suspects in the south side explosion is a good one.

Prosecutors say the explosion in the Richmond Hill neighborhood was allegedly sparked after the suspects removed a stepdown regulator from their home's gas system. The regulator controls the amount of natural gas flowing into the home.

On top of that, a gas fireplace valve was opened or removed.

"It seems pretty clear the plan was to fill the house with gas and set it off," said former arson prosecutor Peter Beering.

Monserrate Shirley, her boyfriend Mark Leonard and his brother, Bob Leonard, were arrested Friday.

Beering trained some of the investigators in this case.

"It's an excellent case," he said. "I would have no qualms taking the matter."

Finding the evidence of those missing valves and the ignition source - a microwave oven timed to fry a piece of metal - shows investigators pulled off "a heroic job," Beering says.

He says evidence shows a pattern of research and plotting by the alleged conspirators.

"Most of those criminal enterprises succeed or fail based on the engineering," says Beering, who also lectures on anti-terrorism issues.

The engineering and planning here allegedly involved the conspirators asking a utility worker one day before the explosion how to spark a natural gas blast.

"Unfortunately, their planning resulted in what ended up being an engineering mistake, because their scheme actually worked too well," Beering said.

Releasing so much gas into the house the blast collapsed a neighbor's house, trapping and killing a husband and wife, Dion and Jennifer Longworth.

A very imperfect crime. Now, the three plotters could face the death penalty.

"So many criminal enterprises have been unwound because of details, missteps and footprints that people leave," says Beering.

In this case, those footprints were found by skilled investigators in a scorched debris field.