The US authorities are now "instrumental" in Garda efforts to bring down the leader of the Kinahan crime cartel, the Sunday Independent has learned.
Security sources said this weekend there is a "plan in motion" to bring Daniel Kinahan to justice in Ireland.
The Garda Drugs and Organised Crime Bureau is "pursuing a specific angle against Daniel" Kinahan and hopes the evidence it is collecting can lead to his downfall.
Sources acknowledged these efforts are being aided by police forces internationally, most significantly in the United States.
It emerged in December that the Dubai-based mob boss is being sued by a boxing manager in the US under organised crime laws.
Kinahan, and sports management company MTK Global, which he co-founded, are alleged to have signed champion boxer Joseph Diaz (28) earlier last year while he was still under contract and offered him $100,000 (€82,000) up front.
This "opens avenues" for US law enforcement agencies, such as the FBI, to get involved further in investigating his activities.
A senior figure in the sport in Ireland said speculation is rife in boxing circles that the Americans are "gearing up" to get Kinahan, adding: "It's not good for him that he's caught the attention of the American authorities.
"Daniel and MTK are dominating boxing on every level. It's not just the world stage with the likes of the Tyson Fury and Anthony Joshua fight. They're also infiltrating the amateur levels of the sport, both in the UK and Ireland," the senior figure said.
"People in the boxing world won't speak out because of fear. Not fear of being murdered, just because he's so powerful in the sport. People, including me, have to be very careful."
Kinahan continues to "expand his domination" on the world boxing stage as well as at amateur level in Ireland and the UK, said the senior boxing figure, who declined to speak publicly for fear of reprisals.
A fortnight ago, Kinahan released a statement to the Irish Independent, claiming to be a legitimate businessman and confirming his continued involvement in international boxing, despite an outcry in the Dáil as politicians tried to derail his involvement in the sport.
"Daniel's statement gave two fingers to gardaí. He all but said to them, 'Come and get me if you can'," a source said. "It is acknowledged in senior Garda circles that there has been a lot of garda talk over the past few years about holding Daniel to account as the leader of this major international drugs cartel, but nothing has happened yet. The pressure is now on."
Irish Amateur Boxing Association (IABA) chief Fergal Carruth declined to comment specifically about the influence Kinahan has on boxing at every level.
He did, however, provide a statement on behalf of the association, outlining its position on who it allows to get involved in boxing and the processes involved.
It said there is a "world of difference between amateur and professional boxing" and that "amateur boxing in Ireland adheres to the highest standards of compliance across all the key measures".
It goes on to highlight the good work the IABA does and points to the strict regulations in place.
"We are proud of the work we do in communities throughout Ireland, including some of the country's most disadvantaged communities," the statement said.
"Those involved in delivering the sport are all Garda- vetted, as is the case with all sport in Ireland. It is totally fallacious to link the two. Professional sport, whatever the sport, is very different to the amateur version of the sport."
However, the Irish boxing figure who spoke anonymously claimed Kinahan and MTK "already have their tentacles" on Irish and UK amateur boxers.
"Boxing appeals to young people on the cusp of criminality," they said. "Boxing can turn their lives around, so we try to get them back to a good place. Then they end up being offered big money to go fight for the Kinahans - the very thing boxing at its purest level was trying to save them from."
Last Monday, a BBC Panorama investigation into Kinahan, who was named in the Irish courts as the head of an organised crime group, repeated assertions that he was the leader of a drugs cartel. It was watched by millions of people.
The programme prompted Kinahan to release a second statement. In it, he again distanced himself from organised crime and reiterated he was a legitimate businessman.
"Daniel is very smart. He knows his boxing and he loves his boxing. He is careful to operate as an agent so he doesn't need to be licensed," the boxing insider said.
"MTK have boxers all over the world, up to 250 on their books. They somehow have the money to buy boxers.
"Daniel Kinahan is destroying this sport. Where are the gardaí who keep telling us they will bring him down?"