Leonard John Warwick's DNA has been matched to at least one crime scene in an extraordinary technological breakthrough that formed part of a substantial brief of evidence that led police to arrest Mr Warwick on Wednesday.

The 68-year-old former fireman and skilled bushman was charged with 32 offences, including four counts of murder, one attempted murder, five bombings and one break and enter between 1980 and 1985.

Police continued to search his semi-rural Douglas Park property for evidence, including explosives, on Wednesday evening after heavily-armed Tactical Operations Unit officers surrounded him in Campbelltown at 11.30am.

"This case has been embedded in the psyche of not only this state, but this country, and investigators are determined to bring finality to the families of victims," Homicide Squad commander Mick Willing said.

It is alleged Mr Warwick targeted judges of the Family Court of Australia, their families, a lawyer and innocent citizens, motivated by a bitter custody dispute with his ex-wife Andrea over access to their daughter Trudi.

The charges include the murders of his brother-in-law, Stephen Blanchard, Family Court judge David Opas, Family Court judge Ray Watson's wife Pearl and father-of-three Graham Wykes, who was killed when an explosion tore through a Jehovah's Witness congregation in Casula.

Deputy Police Commissioner Nick Kaldas said significant new evidence will be put before a court, including historic evidence that has been "enhanced using technology that was probably not available 30 years ago".

Police sources have told Fairfax Media this includes DNA evidence linking Mr Warwick to at least one crime scene.

It's understood several new witness accounts, primarily people who were too scared to give evidence in the past or thought it was insignificant information, have strengthened what was previously a circumstantial case.

The new evidence adds to mountains of historic evidence gathered by a joint NSW and Australian Federal Police taskforce established in the 1980s.

"When you add it all up we felt and we feel that we have a very strong case," Deputy Commissioner Kaldas said.

Rose Parkin, daughter of the late Justice Watson, said she was shocked by the arrest.

"My reaction is a bit of shock and a bit of sadness because it brings back the pain of the time," she told Fairfax Media.

"My father had a vision for a Family Court, it was a very idealistic vision and his wife was killed because of that. That was a very hard thing for him to digest."

Coroner Kevin Waller returned an open finding in 1987 because of a lack of evidence but he would later say that he believed there was enough evidence against Mr Warwick to warrant the matter going before a jury.

The case was re-opened in 2012 by the Unsolved Homicide Squad.

The former detective in charge, Kevin Woods, told Channel 7 in 2013 that O-positive blood was found following a break-in at the Jehovah's Witness hall in Casula that was bombed a week later.

Mr Warwick was also O-positive but no further link could be drawn at the time.

Police said they were not looking for anyone else in connection with the case. However they made repeated requests that anyone with information should come forward.

"Today is an opportunity to think about what you may have that is important to this investigation," said acting state crime commander John Kerlatec.

He said the crimes instilled "a great deal of fear" across Australia at the time and Wednesday's "historic" arrest was about the victims.

"There are many other people who suffered during that time and continue to suffer today," he said.

The Chief Justice of the Family Court, Diana Bryant, said she was "grateful that police have at last made an arrest after so long without any resolution of these crimes".

Deputy Commissioner Kaldas praised "the tenacity of the detectives involved, the professionalism and commitment" shown by the Unsolved Homicide Squad.

Mr Warwick will appear in Campbelltown Local Court on Thursday.