A service was held in the NSW Police Academy Chapel.

Acting principal Quarmby said Constable Nelson was shot by bushrangers on January 26, 1865 at Collector.

"Constable Nelson was at home with his wife and eight children, but decided he had to do something," he said.

"Though his wife pleaded with him not to go, his last words to her were: 'I'll just have to do my best'.

"He faced them and was killed. The story reminds us that we remember those who gave their lives in the execution of duty. It displays the courage of good to always stand up to evil and it also shows the importance of family. The community and the NSW Police Force supported that family."

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Acting Assistant Commissioner Rod Smith said there are 273 names etched on the Wall of Remembrance.

"This has stood for 20 years and it serves to remind officers that the job they undertake can be a dangerous one," he said. "Rank has no meaning today; we stand side in support of those we have lost."

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Three names were added to the Wall of Remembrance this year, including Constable Timothy Proctor, who was killed in a car accident this year. Two historical names were added, Senior Constable Francis Drum, who died in 1882 after falling from his horse, and Senior Constable Colin Young, formerly of the Tactical Operations Unit, who died from suicide in 2016.

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