I led cops to the Hamptons hotel killer who murdered Sabina Rosas - by the time they caught up with him, it was too late

It was a story with all the trappings of a viral Netflix series or a true-crime blockbuster.

A beautiful young artist, an older 'sugar daddy', a lifeless corpse found in a $1,200-a-night spa hotel in the Hamptons - and a killer on the run.

When I was assigned to cover the case just a few days ago, I never imagined I'd come so close to the monster who took the life of 33-year-old Sabina Rosas. 

Or that it would be my tip that cracked this tragic case. 

It was midday on Monday when Sabina's body was discovered at the Shou Subi Ban House, in Water Mill on Long Island, a self-styled 'private sanctuary' featured in the likes of Vogue and Conde Nast Traveler magazines.

Sabina, an artist based in Brooklyn, had been staying there with 56-year-old Thomas Gannon, a man who called her his 'muse'.

But at 8am, four hours before the body was discovered, Gannon had climbed into the back seat of an Uber, fleeing the scene.

As a senior news reporter based on Long Island, I know the district well, including the leafy, picturesque hamlet of Water Mill. 

But I could hardly have expected to run into the Uber driver who unwittingly helped Gannon escape.  

Or to find myself settling down into the very seat where the killer spent his final hours. 

I met Ozan Musullu by chance when, on Tuesday, I took his Uber from Southampton Station to Shou Subi Ban House four miles away. 

It was during this short ride that Ozan revealed the details of his extraordinary encounter the previous day.

He recalled it clearly. Gannon's booking had been unusual for Long Island: an early pick-up at a ritzy Hamptons wellness retreat to take a middle-aged man hundreds of miles away to a cabin in Honesdale, Pennsylvania. 

He remembered too that, after a 220-mile, Gannon failed to leave a tip.

Gannon had been silent, Musullu recalled, saying nothing aside from giving some directions towards the end of their trip. 

He'd spent the first stretch of the drive looking out of the window looking 'miserable' before seeming to pass out, exhausted, in the back. 

Four hours and $370 later - Gannon stepped out and muttered a barely audible 'thank you' before disappearing into a stylish cabin in the Pennsylvania woods. 

There was no blood on his clothes that Musullu could see, but he'd seemed both agitated and exhausted, sleeping for most of the journey. 

Musullu dropped him off, turned the car around and started the grueling haul back to Long Island. 

He was furious not to have received a tip but otherwise he'd taken no particular view. No one at the time knew of Gannon or that he'd fled the state of New York, where an intense murder investigation was unfolding. 

It would later emerge that, once inside the cabin, Gannon had fired a single gunshot into his temple, making a rapid escape from the hell he'd unleashed hours earlier.  

On hearing the driver's testimony, I immediately informed the Suffolk County Police, urged them to speak to Musullu, and gave them the Pennsylvania address where Gannon had been dropped off.

The man, Musullu had told me, gave his name only as 'Tom'. He was tall and fair-skinned, wearing a long black coat.  

When law enforcement officers arrived there on Wednesday, he was dead, leaving Rosas' family outraged that her killer was able to evade justice.

'It was such a cowardly thing - such a cop out. It is shrouded in mystery why Sabina is no longer with us. We will never know what happened,' her grief-stricken partner, Ryder Itawa told me. 

Rosas' injuries have not yet been made public and the police are yet to reveal how Gannon carried out the murder, but they have confirmed that it was 'violent'.

The details of Sabina's complex love life and the nature of her relationship with Gannon also remain unclear.

She was in a romantic relationship with Itawa and legally separated from the husband whose name she was still using at the time of her death. But she was also linked on property records to a third man. 

Itawa ran into this third man at the coroner's office; both men had turned up to identify Sabina's body.  

Itawa says he was aware of her relationships with other men, but tells Daily Mail it was not something they discussed often. 

He described Gannon as 'very odd' maybe 'socially inept' and noticed when Sabina was around him her whole demeanor would change. 

She felt 'trapped' by him 'psychologically', he said. 

'He helped fund her artistic endeavors. She was like his muse of sorts.

'He was head over heels for her but also very possessive... once he told me that Sabina did not love him and told me that he believes Sabina was using him for his money.' 

'A benefactor's money suddenly became the control he would use to stay in her world and her orbit. That is difficult,' he said. 

Liz Phillips, who had been Sabina's mentor and motherlike figure in America, echoed his comments. 

'He supplied her with money to facilitate her adventures and seemed to worship her imagination and various quests. She was bored often but appreciated his help,' she recalls. 

Just a few months before her violent death, Sabina had launched an online fundraiser, appealing to friends for the cash to pursue her artistic dreams. 

Gannon, who was previously married and has an adult son, was the top donor, gifting $1,000 to his young, inspiring muse. 

'You have an amazing gift and soon all the world will see. I love you,' he wrote in a comment accompanying his generous contribution.  

Gannon is believed to have been paying for the $1,200-a-night Hamptons getaway. 

Suffolk County Detectives, while thankful for Daily Mail's help in solving the crime, are yet to reveal exactly when they found him. 

There was no sign of the bloody suicide Gannon resorted to at the Pennsylvania cabin on Wednesday. 

A young woman believed to be Gannon's son's girlfriend answered the door with trepidation, before refusing Daily Mail's questions. 

The house, a stylish and woodsy retreat, is now for sale. 

In an online listing for the property, women's clothes are seen hanging in the primary bedroom closet. 

In the swish master bathroom stands a wooden tub, uncannily similar to the soaking baths in the Shou Subi Ban House suites. 

The police investigation has come to a close with his death. 

The staff and owners at Shou Subi Ban House have been silent, closing for two weeks and refusing all media inquiries.  

On Thursday, Suffolk County detectives thanked DailyMail.com and Musullu for helping them solve the case. 

But for Itawa and for Rosas' family thousands of miles away in eastern Europe, the misery has only just begun.