Samiuela Anania Tupou, 21, died at Seaside Park in Ōtāhuhu in the early hours of May 25.
He was found in critical condition and later died at the scene despite medical attention.
Stuff.co reports Tupou had just recently returned from the United States to live with his family in Mangere before he died.
No arrests have been made, police said.
Counties Manukau CIB detective senior Sergeant Malcolm Hassall said Tupou had no criminal history and they believed the offender was not known to him.
He said investigations were ongoing.