Patience, persistence, attention to detail and a memory that never forgot a face or name made Chris Nielsen a standout police detective, his colleagues said.

Nielsen, who retired in August after a long career with Roanoke County law enforcement, died Wednesday of an apparent heart attack, his family said. He was 48.

Nielsen joined the Roanoke County Sheriff's Office in 1984 after working as an officer in Fairfax County. In 1990, he transferred to the new county police department.

His career included an unsuccessful run for Salem sheriff in 2001 and work investigating homicides and crimes against women and children.

But it was his skillful interrogations, and his passion for the work he did, that his colleagues said they will remember most.

Nielsen could develop a rapport with witnesses and suspects and get information from them that helped solve cases, said Lt. Chuck Mason, who worked with Nielson for 17 years.

The combination of his patience and attention to detail was often a problem for suspects who were trying to spin a tale.

"Chris was very good at really listening to what they were saying, and he could pick their statements apart," said Lt. Huck Ewers with the county police department.

Nielsen worked for several years investigating crimes against women and children.

"He took it to heart when somebody was assaulted," said Pamela Gold, domestic violence specialist for the Roanoke police department. "It just wasn't a case number to him."

It was not uncommon for Gold to get phone calls from him at night or on the weekends when a domestic violence case involved the county and city, she said.

He took his passion to Prevent Child Abuse Roanoke Valley, which later evolved into the Children's Advocacy Center of the Roanoke Valley, where he served on the board of directors.

There, he helped with tasks from fundraising to working with families.

"He made them feel like their worries were being listened to," said Shannon Brabham, former executive director of Prevent Child Abuse Roanoke Valley.

Just as he never forgot a name, he also never forgot the cases that he hadn't closed.

Even as he was getting ready to retire, he was still trying to solve a rape that happened in the 1990s, Mason said.

"He really hated not to clear cases," he said. "He took very seriously his police officer's responsibilities to the victims."