• Woman believed to be partner of John Doe, Letha Mae Montemayor, arrested in California on January 4
• Arrest warrant for John Doe issued in California... but he could be anywhere in the world
  

By Louise Boyle

PUBLISHED: 08:21 EST, 28 March 2013 | UPDATED: 09:11 EST, 28 March 2013

Investigators are coming closer to capturing a prolific porn distributor who has evaded authorities for more than a decade - but still can only be identified through this one, blacked-out photograph.

'John Doe' is being hunted by the Department of Homeland Security's Cyber Crimes Center using the latest technology which hones in on tiny clues.

Investigators, who work in Fairfax, Virginia, work with their peers all over the world to track down the sexual predators.

Experts delve into the horrifying world of child pornography to track down the pedophiles. Even the smallest clue, such as a plug socket, can bring them closer to making arrests.

Child Exploitation Investigation Unit Chief Patrick Redling told NBC this week: 'Once that image is taken of the child and the abuse that's occurring, it's on the Internet forever.'

Year on year, the number of arrests have piled up. In 2010, 912 pedophiles were arrested by Homeland Security but by 2012, that number had almost doubled to 1,655 predators.

In January, a woman believed to be the partner of John Doe was taken into custody.

Letha Mae Montemayor, 52, was arrested outside a San Fernando Valley apartment complex in California on January 4.

Montemayor was suspected of making and appearing in child porn photographs a decade ago.

She faces charges of producing child pornography and conspiracy, officials said. Each charge carries a minimum 15-year prison sentence.

In the incriminating photos, the woman believed to be Montemayor, appears to be molesting a young girl.

Forensic experts believe the shots were taken about 11 years ago in San Fernando Valley. A phone book and calendar were seen in the shots, officials said.

The images were first discovered by ICE agents in Chicago in 2007. A man was also seen in the photos.

The woman in the photos had several distinctive tattoos, including a butterfly on her hip and a curled-up cat on her right shoulder.

Claude Arnold, special agent in charge for Homeland Security Investigations, said: 'The images in this series have been identified in connection with more than 275 child pornography investigations across the country.

'The reality is, every time a photo or a video of an innocent child being sexually exploited is viewed, that victim is violated again.'

An arrest warrant has been issued for John Doe in California but investigators admit that he could be anywhere in the world.