Lajos Gyorgy Kvalka, 48, surrendered to police on Samui as the net closed on him and was brought to Phuket last night by Tourist Police.
Mr Kvalka admits to being in the room when another Hungarian, Moshe David, bashed and stabbed Peter Reisz, 47, to death at a house in Phuket City late last month.
But he denies having been a participant in the killing. Mr Kvalka is likely to face further intense questioning today about why he did not go to police earlier.
According to police at Phuket's Tungthong Police Station, where Mr Kvalka is being held, Mr David, 38, confessed to killing Mr Reisz, a former business partner.
He also took part in a reenactment of the murder at the house in Phanason Residences, near Makro in Phuket City.
It's unclear at this stage whether Mr Kvalka was with Mr David when Mr David bought large black plastic bags on a shopping trip to Central Festival Phuket in which to hide Mr Reisz's body.
However, it's likely that two people would have been required to lift the dead man into his own white pickup.
Mr Reisz's body was dumped in jungle on Phiket near Patong Hill, not far from the house where the killing took place.
Mr Reisz's pickup was later found on Samui, where it had been placed on sale for 500,000 baht.
Mr David was arrested at an ATM at the MBK shopping centre in Bangkok. It's not known whether he returned to Samui with Mr Kvalka after the killing, or went straight to Bangkok.
Both men are likely to appear in court shortly on charges relating to the murder. Police will also be keen to question Mr David about the disappearance of Hungarian billionaire Laszlo Csepai in Thailand earlier this year.