Former All Black Mils Muliaina thought he was being pulled over for a drugs test when police arrested him in relation to sexual assault allegations following a match, his manager says.
The World Cup-winning player, who is currently signed to Irish side Connacht, had "no idea" he was about to be arrested, his manager Simon Porter said.
Muliaina spent a full night in police custody after his arrest in the United Kingdom, following his team's 14-7 defeat to Gloucester in the Challenge Cup.
He was led away from the ground and put in a police van minutes after the match. The incident was captured on Sky Sports cameras.
Muliaina was taken to Cardiff for questioning over an alleged sexual assault in the Welsh capital last month. He has since been released on bail without charge.
"When he got approached as he was walking off the pitch he thought he was getting drug tested," Mr Porter said on Newstalk ZB this morning.
"He just had no idea what was coming and was just as shocked as everyone else."
Asked if the dramatic arrest was grandstanding by police, Mr Porter said: "I just can't comment on that.
"I guess that what they've deemed is that somehow he was a flight risk. I guess given that he was living in Ireland they waited until he was back on British soil before they took any further steps."
Connacht played the Cardiff Blues in the Welsh capital on March 6, but it is not known what date the alleged incident is said to have occurred.
Mr Porter had spoken to the player and his lawyer Matthew de Maid this morning.
Muliaina was "better than I'd be if I was in his situation", Mr Porter told Newstalk ZB.
"He's just distressed I guess, in shock."
The 100-capped player "denied any wrong-doing", and would fully cooperate with the police investigation, Mr Porter said. He had been released, and would travel back to Galway, but had agreed to return to Cardiff to speak to police in July, he said.
It was not yet known whether he would continue playing for Connacht while the investigation was carried out.
"That's all stuff that we have to work out. We're just rolling with one step at a time," Mr Porter said.
"I'm pretty confident that Mils' career is going to continue, that this is just something that we're going to have to work through. I'm pretty confident that as time elapses and more information comes out that this isn't going to have any affect on his rugby playing future.
"I don't know what Connacht are going to do in the short term. We'll get him back to Galway and worry about that when we can.
"People up there have been talking to Zebre, his new club, and keeping them abreast of what's going on and as much as we know, and I'm pretty confident that come August or September he'll be in Italy doing his job."
It was "just a matter of wait and see what happens next" in relation to the police investigation, he said.
"He hasn't been charged, they haven't indicated whether he will be charged. He's just agreed to return to Cardiff if and when required."
Mr Porter urged people "not to jump to conclusions".
"There's lots of things I'd like to say, but there's an on-going police investigation and we're just going to have to bide our time on that sort of stuff," he said.
"The whole thing came as a shock to Mils. The manner in which it happened ... caught everyone a bit by surprise, and has added to the shock and distress. And particularly Mils is feeling for his family back here, so we're just rolling with the punches here at the moment and letting the dust settle."
Muliaina's family are yet to make any comment on the arrest.
His sister-in-law Corinne McBurney today told NZME. News Service that the family would not be commenting on the incident.
The Grey Lynn home of Muliaina's estranged wife Hayley Muliaina appeared to be empty today, and no-one answered the door.
Muliaina split had from his wife - who is the mother of his 6-year-old son Max - and it is understood he has a new partner in Ireland.