But there behind the four-bedroom property in Sydney's north-west, Detective Inspector Bryson Anderson probably didn't even see his alleged attacker's final move.

It is understood the detective and another officer had sneaked around the back of the sprawling Oakville property as others stayed at a barricade at the front, edging close to the home to try to bring a two-hour siege to a peaceful end.

He pleaded with Mitch Barbieri, 19, to put down the crossbow and end the stand-off that had begun just after 2pm with an ugly dispute with his neighbour, the tow-truck king Kevin Waters.

But as Inspector Anderson stood on the back patio apparently sheltered from crossbow arrows, he was struck with a knife, its blade piercing the policeman in the neck and chest.

Inspector Anderson's wife Donna has been left a widow, his three children aged nine, 11 and 15, fatherless.

Police swooped and handcuffed Mr Barbieri, also arresting his mother, Fiona, 45.

Initial calls to paramedics had indicated the officer was struck in the head with an axe but it appears this was confused by allegations that Fiona Barbieri was seen brandishing a large metal mallet shortly before Inspector Anderson was fatally wounded.

Detectives have charged both Barbieris with murder but will allege that Mitch, once a promising junior rugby league player, inflicted the fatal wound.

Inspector Anderson's family described him as a ''dedicated and loving'' husband, father of three children, son, brother, uncle and friend.

A brother, Damian Anderson, delivered the family's statement, flanked by his brother Warwick, a former-policeman-turned-lawyer, his retired policeman father Rex, and Donna. ''Our family cannot adequately express the devastation that follows the loss of Bryson,'' Damian Anderson said on Friday.

''Commensurate with our sense of loss is the pride we have in a man who has given his life in the service of the people of NSW.''

The sentiments were echoed by the Police Commissioner, Andrew Scipione, who, with the Deputy Commissioner Nick Kaldas and Assistant Commissioner Denis Clifford, appeared deeply affected by the death of an officer all knew well.

Inspector Anderson had followed his father, a widely respected superintendent, into the force, Mr Scipione said.

Mitch and Fiona Barbieri stayed in the cells when their matter was heard briefly at Penrith Local Court on Friday. Neither applied for bail and it was formally refused.

Documents before the court said they had shown no remorse and denied the charge of murder.

Mr Scipione said there had been a protracted dispute between two families and detectives from the Hawkesbury local area command were aware of disturbances on Scheyville Road.

It's understood the Barbieris lived next to tow-truck king Kevin Waters, who was ''devastated'' that an officer had lost his life.

But it's believed police were called about 2pm after Mr Barbieri fired an arrow from his crossbow onto Mr Waters's property, which narrowly missed a tradesman.

Crime scene officers found an arrow in Mr Waters's aviary.

A wall of flowers and a simple sign describing Inspector Anderson as ''an officer and a gentleman'' marked the tragedy at his station, Windsor.

with Bellinda Kontominas, Rachel Olding