Caster Semenya was an unknown until a few months ago
The coach of South African athlete Caster Semenya, the 800m world champion, has resigned amid an ongoing investigation into her gender.
Ms Semenya, 18, was told to take gender tests after winning gold at the World Championships in Berlin.
Wilfred Daniels said he was leaving as coach as Athletics South Africa (ASA) did not advise Ms Semenya properly.
He said he was sorry for not protecting her from all the media attention, which ASA should have predicted.
"I'm so sorry for the part I played; because of my negligence she went through all that," he said, South Africa's Star newspaper reports.
The controversy over Ms Semenya's gender has angered many in South Africa, including her family who insist she is female.
'Gender test trick'
Mr Daniels said a month before the World Championships in Berlin, ASA knew about the IAAF's concerns about Ms Semenya after she won a gold medal at the African Junior Championships in Mauritius.
Given this knowledge, he said, ASA should have done more to help her deal with the questions over her gender after she won gold at the World Championships in Berlin.
He said that in July the ASA complied with the IAAF and gave Ms Semenya a gender test.
He said she was tricked into taking what she believed were standard drug tests.
"She was asked to go to a clinic in Pretoria to undergo some of these tests but the tests were not explained properly. According to the source I spoke to, it was actually some kind of gender verification test," he told South Africa's Talk Radio 702.
But ASA has always denied it had a hand in any gender verification tests.
The results are still not known and following her performance in Berlin, the athlete has been told to undergo further tests.
Mr Daniels has personally apologised to Ms Semenya for how the matter was handled.
"I had to leave. I just looked at myself and asked if I liked what I saw," he said.
"I asked if I could really enjoy my life knowing what I know... My conscience was too great.
"I am not happy. I'm not pointing fingers at anybody because I am part of the collective responsibility and blame."