Sunday World can reveal that a series of raids, leading to two arrests, were carried out across west Belfast and Co Down last week as part of the probe into Warren Crossan's murder.
Last Monday, a property in Downpatrick was searched and eight other homes in west Belfast were also raided in a major police operation across three days.
Some of those targeted included high-ranking Oglaigh na hEireann (ONH) members, leading to speculation that the gang played a part in the father of two's gangland execution believed to have been revenge for the killing of Dublin criminal Robbie Lawlor.
One leading dissident republican targeted in the PSNI's Major Investigation Team searches was former New IRA man Tony McDonnell.
The 49-year-old - once quizzed over the Regency Hotel shooting in Dublin - had his west Belfast home searched by murder cops.
A close friend of the Ballymurphy-born dissident, jailed in 2013 for collecting information on police officers, also had his property raided.
Two men, aged 49 and 33, were also arrested under the Terrorism Act and were taken to Musgrave Serious Crime Suite where they were later released after questioning.
McDonnell, who previously told this newspaper that "dark forces" were behind his arrest over the 2016 Regency Hotel bloodbath which fuelled the deadly Hutch-Kinahan feud, has previously been under threat from rival dissidents.
Crossan (28) was shot dead in broad daylight as he visited his mother on St Katharine's Road in the St James's area of Belfast on June 27 last year.
Cops believe his callous killers waited for several hours before chasing him and shooting him multiple times.
The 28-year-old was targeted in what is believed to be a revenge attack following the murder of gangland enforcer Robbie Lawlor in Ardoyne in April 2020.
Warren was the son of murdered dissident republican chief Tommy Crossan, killed at a fuel depot in Belfast on Good Friday in 2014.
It is suspected the dad of two was killed for providing the getaway car used in the killing of the gang enforcer Robbie Lawlor.
At the time of his murder, Crossan was on police bail accused of possessing £180,000 of cocaine with intent to supply after he was arrested in Lisburn.
Speaking about this week's police operation, Detective Chief Inspector Michelle Shaw said: "The two men, aged 33 and 49, were arrested in the west Belfast area on Monday July 5 under the Terrorism Act and taken to the Serious Crime Suite at Musgrave Police Station. They were subsequently released following questioning.
"A property was searched in Downpatrick on Monday and eight properties were searched in the west Belfast area between Monday and Wednesday as part of our ongoing investigation into Warren's murder.
"A number of items were seized for further examination.
"I am continuing to appeal to anyone who has information, no matter how small, to contact us on the non-emergency number 101, or submit a report online using our non-emergency reporting form via http://www.psni.police.uk/makeareport/. You can also contact Crimestoppers anonymously on 0800 555 111 or online at crimestoppers-uk.org."
On the anniversary of his death last month, the senior cop made a fresh appeal over the murder.
DCI Shaw said the Crossan family "deserve to have answers and these dangerous men need to be removed from our streets".
New CCTV and images of the suspected gunmen were also released.
The Detective Chief Inspector said: "One year on from this brutal murder my investigation continues to progress and I am releasing further CCTV footage of the two men I believe murdered 28-year-old Mr Crossan.
"The first piece of CCTV footage is of the two suspects crossing the junction of the Falls Road that joins the Whiterock Road and St James's Road at 8.37am on the day of the murder. I believe that the man on the purple-coloured mountain bike arrived from the direction of Turf Lodge and turned onto the Whiterock Road just before 8am. I believe they both then leave together from the Whiterock estate approximately 40 minutes later.
"They then travel along St James Road where a minute or so later they turn left into St James Crescent. The gunmen then lie in wait for several hours until Warren arrives at his mother's house in Rodney Parade at approximately 12.20pm.
"Approximately 30 minutes later the gunmen can be seen appearing on foot from an alley way between St James Road and Rodney Drive.
"They chase Warren into St Katharines Road where he is shot multiple times and left to die in the street.
"The gunmen then make good their escape back along St Katharines Road into the same alleyway.
"Warren's family deserve to have answers and these dangerous men need to be removed from our streets. This callous murder was carried out by individuals who have no regard for life."