Tall, dark and handsome, Glenn Mills was a smooth talker dubbed the "HIV Predator".

Until his death in Auckland's Mt Eden prison this week, the 40-year-old train driver was facing 14 allegations of infecting, or attempting to infect 14 people with the potentially-lethal disease.

Seven of his partners tested positive for HIV after having unprotected sex with Mills. One woman fell pregnant after sleeping with him: the unborn child tested negative.

His case is unique in New Zealand.

While other men have been found guilty of passing HIV to partners, none had slept with as many people - both men and women - as Mills.

Reports that a man was intentionally spreading HIV first reached Auckland Regional Public Health Service in March.

Health officials then had to check the veracity of the reports, while also wrestling with last winter's swine flu outbreak.

The inquiry was made more difficult by the sensitive nature of sexual health, said clinical director Dr Julia Peters.

"People are concerned about their individual well-being but to extrapolate that to concern for public health, is a step sometimes that people - who are already grappling with something that is very serious - are not in a position to take."

At the same time, members of Auckland's gay community also began investigating the rumours.

GayNZ website writers Jay Bennie and Matt Akersten approached the Auckland DHB with their concerns in early May, but say they were "fobbed off".

But Mr Bennie learned - just three days later - that health staff had called a meeting with Auckland police.

Bolstered by confirmation of an inquiry, GayNZ broke the Mills story online. It was followed up by TVNZ current affairs show Close Up.

GayNZ's coverage of the issue - which described Mills as an "HIV predator" - encouraged a young man to lay a formal complaint with police. Charges were laid against Mills a fortnight later, after three other men - all aged between 17 and 31 - also spoke up.

Still more complainants came forward after Mills' name suppression was lifted on June 19 and his photo appeared on the front page of the Weekend Herald.

About 100 people came forward to be tested for HIV after the Mills media coverage.

Auckland Adult Sexual Assault Team head Detective Sergeant Andy King said the investigation into Mills had a number of unusual elements, including the number of potential and actual complainants, and the fact both men and women were involved.

That the sexual encounters were consensual was another complicating factor, he said.

"The sensitivity of HIV infection was a challenge for complainants to disclose to police, as the sexual element in this case occurred with consent. Virtually all of the complainants were concerned about their privacy and identity becoming public knowledge."

Police say Mills set up aliases on internet sites and chatlines, and a telephone chatline.

Despite having been diagnosed HIV-positive in May 2007, Mills always insisted he was "safe" or "clean".

He would then persuade his partners - many of whom believed they were in a monogamous relationship with Mills - into unprotected sex. If a partner insisted Mills use protection, he would deliberately remove or rip the condom.

One complainant was an ex-boyfriend living in Japan who reunited with Mills on a cruise ship in Florida.

The pair had unprotected sex while on the eight-day trip and the 25-year-old man learned he had contracted HIV on his return to Japan.

Although the sex offending happened in international waters - and therefore outside New Zealand the jurisdiction of New Zealand authorities - police were able to lay charges through a previously unused section of the Crimes Act.

But eventually, some of his partners would become sick. When confronted over whether he was HIV positive, Mills would react angrily.

In one text message to a 24-year-old man, he denied being infected, saying: "I'll give a medal to the person who gave it to you. I hope you die quickly." But another text, in which he referred to his "infected seed", revealed he knew of his condition.

When a 23-year-old man who met Mills at the Centurian gay spa off Karangahape Rd was diagnosed as HIV positive, Mills pretended to be safe but promised to get tested again.

The Mills case has helped to highlight gaps in legislation dealing with the reckless or wilful spreading of disease.

Confidentiality clauses in the Public Health Act prevent health professionals disclosing that someone is HIV-positive, or could be spreading the virus.

Only if medical staff believe a person poses a risk to the public - as in the case of Mills - can the public health service be notified.

Mills was found dead in his cell on Monday morning, just hours before he was due to return to Auckland District Court.

The man who laid the first formal complaint against Mills - and was due to give evidence against him - told GayNZ.com he was saddened by Mills' death, but also relieved he had been spared a trip to court.

"The anxiety of knowing that sometime soon I would have to stand up in court and reveal so much to strangers, and be cross-examined about intimate aspects of my life, has been intense . At times it has been overwhelming ... I think I may get some closure on this now. I hope so anyway. But this is not the way I would ever have wanted it to happen."