AFL player manager Ricky Nixon will check into a rehabilitation clinic to have treatment for a "substance problem".

It is the latest stunning development in the drama surrounding Melbourne 17-year-old Kim Duthie, with one of the AFL industry's most prominent men saying he would take an indefinite break from his work.

Nixon returned to Australia on Sunday. He'd left two weeks ago, within days of admitting having "inappropriate dealings" with Duthie.

But he continues to deny her allegation that they had a sexual relationship.

In a statement released to AAP on Sunday night, Nixon also said he would co-operate fully with the AFL Players' Association (AFLPA) investigation into his alleged involvement with Duthie.

"After 20 years' involvement in player management, I am now taking an indefinite break to deal with a number of personal health issues," Nixon said.

"It is important for both my own health and wellbeing and that of my family to do so immediately.

"(While overseas) I had the opportunity to seek help for my personal issues.

"With the understanding and support of family and close friends, I have decided that I will go to a rehabilitation clinic to seek treatment for a substance problem that has impacted on my life and my decision-making, particularly over the last eight weeks."

Nixon added he had been in touch with the AFLPA, which oversees player managers, during his time overseas.

"I have stated that I will co-operate fully with the investigation currently being undertaken by David Galbally QC," he said.

"I stand by my original statement in relation to this matter."

Nixon thanked the staff at his management company Flying Start and the players he manages for standing by him.

"I am so lucky to have the support of my employees and the players that I manage and while I know this time has not been easy for them, I think it is important for both staff and players at Flying Start that I immediately relinquish all responsibilities and activities a player manager would normally undertake," he said.

Nixon asked for the media to respect his privacy and that of his family and friends, while also apologising for the impact of the scandal.

"As someone who has been involved in the football industry for more than 30 years, I understand the interest in this story but I do ask for the privacy needed to be able to undertake clinical treatment without the intrusion of the media," he said.

"I also ask that the media leaves my family, friends, staff and players alone. I know these events have caused them enough distress.

"This is a significant challenge and one that I am committed to get through and coming out a better person.

"I would like to sincerely apologise to everyone for the impact caused by these recent events."

Ms Duthie reportedly spent much of Monday being interviewed by police.

Last year, she posted on the internet nude photographs of AFL players managed by Nixon and last month released a video she claims was of Nixon and herself in a hotel room.

Nixon's return to Australia coincided with Ms Duthie's appearance on the Nine Network's 60 Minutes program in which she admitted she lied about being pregnant to St Kilda player Sam Gilbert.

She claimed in May last year that Gilbert was the father of twins she was carrying, sparking a scandal that has enveloped players, the AFL administration and Nixon.

Ms Duthie also earlier claimed to have taken photographs of a naked St Kilda captain Nick Riewoldt and other players in a hotel room.

It later emerged she had stolen the photos from Gilbert's laptop computer.

On Sunday night, Ms Duthie admitted lying about her pregnancy and about miscarrying the twins, apologising to Gilbert.

Nixon, who could lose his accreditation if the AFLPA finds he breached his obligations as a player manager, has strongly denied having a sexual relationship with the teenager or using drugs in her presence.

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