Sometimes arrests in homicide cases come almost immediately. Other times, they can take much longer.

In August 2007, Wasel Ali was found dead on a secluded dirt path in Hickory Ridge. After more than four years, Howard County police announced that Ali's twin brother, Wael Ali, had been arrested Sept. 15 in Georgia and would be charged in the case.

The person leading the case was Special Investigator Nick DeCarlo, the violent crimes section's cold case investigator who joined the department soon after he had retired in 2005 after 31 years with the Montgomery County Police Department.

An investigation becomes a cold case "when the case has run its course with no new leads and nothing left to do," said Det. Lt. Brook Donovan, commander of the department's criminal investigation division.


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It also can become a cold case if the primary investigator has left the violent crimes section, been promoted or taken retirement.

It has been more than two years since a Halloween party at Manorstone Lane in Columbia ended early Nov. 1, 2009, with nearly two dozen gunshots. Aaron Brice, a 19-year-old from Silver Spring, was killed. A Columbia man was left paralyzed.

Two men were arrested, but prosecutors ultimately had to drop charges against them. The investigation remains open and is not a cold case.

"To this day I'm still working that case," Det. Dave Chesno said. "We thought we had a strong identification at the beginning of the case. It turned up they weren't our shooter. I'm still working different leads and trying to find more information."

He thinks about it every day, he said. The flier from the victim's memorial service hangs in his cubicle.

Donovan said leads in the case are being followed up on. No stone will be left unturned, he said.

"We start with the big stones and work our way down to the pebbles," he said.

Detectives go back and check information and stories provided by witnesses and those involved. They listen to recordings of past interviews, interview people again to see if stories or memories have changed, and even return to those who might not have been cooperative to see if the passage of time has softened their stances.

"The key for this," Donovan said, "is we don't stop."