A rented jet-ski collided with another at high speed fatally injuring a Victorian woman.
Ms Collie suffered neck and shoulder injuries in the crash and died while being taken to hospital.
Thai police say the 22-year-old partner of Australian woman Emily Jayne Collie, is to face charges of reckless driving, causing death, following a tragic weekend jet-ski accident.
Family members of Mr Keating and Ms Collier, who arrived in Thailand a day earlier, accompanied him to the police station.
Lifeguards pulled Ms Collie from the water and, with her partner, attempted to revive her on the beach. She was pronounced dead on arrival.
Collie's family formally identified her body in Phuket on Wednesday. His girlfriend, 20-year-old Emily Collie from Victoria, died after their jetskis crashed on Sunday.
"Words can't describe how devastated we are", another friend wrote.
Ms Collier, from Kyabram, north of Melbourne, had been a student at Charles Sturt University.
"We did not allow any media or reporters to come inside the inquiry room while police investigator talked with Mr Keating", he added.
Mr Keating's sister, Bree Lyon, told Fairfax the family was "absolutely devastated".
"From the very moment I met you I loved you, I cherished your genuine heart, and that lovely smile".
"I am beyond proud of you Em and I'm really going to miss you more than you could possibly imagine".
"I love you so much Emily and I wish I could just bring you back into my arms", he wrote. I'll always be your boy and you'll always be my girl!
A spokeswoman for the Department of Foreign Affairs and Trade said for privacy reasons she was unable to provide further information.
Under Thai law, the offense is punishable by up to 10 years in jail.
However this had improved in recent times after local authorities cracked down.
Tourism is a crucial pillar of Thailand's economy, but accidents involving travellers are common amid lax and often weakly enforced safety regulations.
Australian media said Keating may not have seen his girlfriend's jetski because of strong sunlight reflecting off the sea.
More than 20,000 Australians holiday on Phuket each month.
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