"Good cases that come to my office mean my prosecutors seek lengthy sentences and lengthy sentences mean you're not on the street to commit another crime," he said.

He also acknowledged that the characteristics of the crimes play a role. "The chances of a Baltimore County citizen being killed by a random act of violence here in the county is really quite low," he said.

Johnson noted residents' cooperation with police, which he said is not earned overnight. "You have to develop that. It's not something you can just change in a year. It's taken, frankly, decades."

The night that Holiday was shot, county police officers canvassed the area, trying to locate witnesses. One man, who was outside smoking, noticed a strange Pontiac G6 speeding past without its lights on.

In court, prosecutors connected Michael Martin and Mikal Martin, to the vehicle through witnesses and car rental records.

Holiday's girlfriend received a life sentence in the killing and Mikal Martin was sentenced to 30 years. Michael Martin's sentencing is scheduled for April 16.

But as one case draws to a close after nearly a year, investigators still have four unsolved cases from 2013 — which means, despite their achievements, their work is never done.

"I'm just hoping and praying they catch the person or persons or whoever," said Robin Flanigan, who remains hopeful detectives will make an arrest in the case of her son, Ryan Evans. Evans, 30, was found shot behind the wheel of his Honda Odyssey near his Gwynn Oak home Dec. 9.

"I don't know who would want to do harm with him," she said.

She said Evans was a father of two and was studying engineering at Morgan State University, and had worked in the records department of the Baltimore County Detention Center where he met his wife Whitney. His mother-in-law is the jail's director.

"They're holding on. Everyone is in a state of shock," she said. "You never think something like this would happen to a member of your family."