Mr Tas, an Israeli student, and his best friend and fellow searcher, Joe Kariv, were scheduled to leave New Zealand today after searching for Ms Okin (35) for more than a month.
Mr Tas initiated a private search for his sister two days after police called off the official operation on April 22.
Ms Okin was last seen leaving Mackenzie Hut on the Routeburn Track by herself on the morning of March 26.
Now Mr Tas has to make arrangements for her body, once it is released following the autopsy scheduled to be held in Dunedin today.
The body was transferred by road to Dunedin last night after searchers found it yesterday afternoon in the area of Roaring Creek, Sergeant Steve Hutt, of Queenstown, said.
"She was caught up within the creek area," he said.
He described the creek as a "proper boulder river course.
Roaring Creek is fed from three major sources".
Mr Kariv told the Otago Daily Times last night it was a difficult time for his friend, who was too upset to talk about it.
Mr Kariv said they did not know what arrangements would be made for Ms Okin's body but Jewish custom was for burial the next day, if possible.
"I don't know what will happen.
''I'm not a religious person, so I am trying to understand myself," he said.
The men were unsure what they would be doing today or whether they would travel to Dunedin after staying in Queenstown last night.
Mr Kariv said he had not spoken to Ms Okin's family in Israel but wanted to thank everyone who had helped in the search.
"We are really grateful for all the kindness from all over New Zealand, but especially from the people of Queenstown, who gave us comfort in times when we needed it."
Police spokesman Inspector Andrew Burns, the acting Otago rural police area commander, said last night police were still trying to determine what had happened to Ms Okin.
He said he had no reason to believe there were any suspicious circumstances surrounding her death.
But police were still trying to determine why Ms Okin's belongings and her body were so far off the track in an area described as precipitous and dangerous. He said it was a difficult area to get in to and out of.
After notifying Ms Okin's family, police confirmed at 1.10pm yesterday that her body had been found.
Police were alerted by searchers late on Thursday afternoon that they had discovered her backpack and camping equipment near the Routeburn Track.
A search party of eight people, comprising police, alpine rescuers and members of the private search team were flown by helicopter from Queenstown to the site yesterday morning.
Insp Burns said while she was found in an area he believed had not been searched, it was not an area he would expect to find someone who had simply missed the track.
Because her body was found so far off the Routeburn Track, he doubted if anyone would have heard her if she had called for help.
