It was a moment 35 years in the making but Leonard John Warwick's arrest on Wednesday was hardly glamorous.

It came on a treadmill in a rehabilitation gym on the outskirts of Sydney, in front of several other patients in their 60s and 70s.

Mr Warwick, 68, was charged with 32 offences relating to a string of bombings and shootings that allegedly targeted judges of the Family Court of Australia, a lawyer and other innocent citizens distantly connected to a bitter custody dispute Mr Warwick was in with his ex-wife Andrea.

Four people were killed and five bombs tore through the homes of judges and a Jehovah's Witness congregation.

Mr Warwick did not apply for bail in Campbelltown Local Court on Thursday and sat quietly in court wearing an old purple jumper and blue jeans.

One regular at the Fit HQ gym on Tindall Street in Campbelltown could hardly believe her eyes when detectives surrounded the same man on the treadmill in front of her at 11.30am on Wednesday.

Mr Warwick, a former fireman and soldier, was a regular at Fit HQ's rehab facility, a separate facility that offers physio and exercise regimes for patients dealing with diabetes, arthritis, heart disease and other chronic health diseases.

As his nearby home in semi-rural Douglas Park was being raided by police, detectives in suits gathered outside the gym.

"I was with another lady on the treadmills and I just happened to look out the door and told her there were a lot of detectives standing outside," said the 69 year-old patient, who asked to remain anonymous.

"We watched them come in and they walked over to the bloody line of treadmills right in front of us."

Mr Warwick, dressed in a grey T-shirt, cream cargo shorts and black sneakers, simply kept walking as detectives surrounded him.

"It was all very quiet, there was no big fuss or anything," the woman said. "They were talking to him and he just kept walking on the treadmill."

Mr Warwick was taken to a patient consultation room that was all glass, still in full view of the gym, before being handcuffed and led out the glass doors of Fit HQ.

"There were so many police around him. Stupid me, I turned round and said 'why are there so many police, he looks like a nice man'," she said.

Dawn Wilson, who was also at the gym during the arrest, said Mr Warwick had been going to HQ at 11am every day for years.

When she later saw him on the news, she said she was "absolutely mortified".

"I was on the bicycle and he'd come past and said 'g'day,' as he always did, and filled up his water bottle then starting walking on the treadmill. He was always the quietest, calmest person."

Detectives were backed up by heavily armed police from the Tactical Operations Unit due to the fear that Mr Warwick could be violent.

He has previously refused to give any help to investigators and has threatened those who have tried to speak to him about the seven attacks between 1980 and 1985.

Former detective Ken Woods told Channel 7 in 2013 that Mr Warwick refused to give a blood sample, be in a suspect line-up, be interviewed or be examined by a doctor in the 1980s.

When crime author Debi Marshall knocked on his door in recent years, he told her: "Get the f... off my property. Now."

After more than three decades, police were recently able to match Mr Warwick's DNA to blood at one crime scene, providing the extraordinary technological breakthrough that led to his arrest.

Statements from new witnesses who were previously too scared to come forward will also be included in the brief of evidence.

Outside Campbelltown court on Thursday, Detective Chief Inspector Pamela Young said there had been "dangers" associated with the case.

"[That's why] we haven't announced what we have been doing along the way so I imagine a few people are surprised," she said.

"We have been working a long time for the victims and the community in the shadows and now we are very happy to have our case listed by the courts."

Magistrate Robert Rabbidge ordered Mr Warwick to appear in court after his legal aid solicitor asked he be left in the holding cells.

He made no application for bail and will return to court next week.

with Nick Ralston