Thirteen years ago, on a freezing winter evening in December, a middle-aged man surnamed Cao from Beijing claimed he had been abducted by aliens and to have cured a Chinese girl using "alien energy" in Qinhuangdao, Hebei Province. His account was met with both skepticism and trust, but Zhang Jingping was one of the only people who devoted time and energy to investigating the matter.

Zhang, 43, director of the investigation department of the World Chinese UFO Association and owner of a private advertising company, launched an independent investigation into the case in 2000.

Zhang, a firm believer in UFOs, believes Cao's case is the most reliable of all the cases he investigated.

"The prevailing opinion among scientists is that UFOs do not exist because they can't explain these strange phenomena, but as more and more people show interest in studying aliens, I believe our efforts will eventually pay off," he told the Global Times.

As part of the investigation, Zhang hired professionals to hypnotize Cao and give him a lie-detector test, a previously unused method of questioning UFO witnesses in China. Cao passed the test. He also brought Cao to the police station and made a computer-generated image of the girl he claimed to have cured. In 2002, he led a group of students to search for the mysterious girl in the county of Qinhuangdao, home to a population of 400,000.

They eventually found the girl, who was then 15 years old. However, she was not a reliable witness as she was mentally unstable. The case was left unsolved, like many other cases Zhang has investigated because there was no "hard evidence" like forensic traces and photos.

Extraterrestrial probings

Over the years, Zhang has investigated many major UFO witness cases, including the juicy UFO abduction case of Meng Zhaoguo, a then 29-year-old farmer from Heilongjiang Province who said he was abducted by aliens in 1994 while he and other farmers were working in the field.

In the spaceship, Meng said a 3-meter-tall female alien who had 12 fingers and braided leg hair approached and asked to have sex with him. They reportedly engaged in a 40-minute long intimate exchange. Afterward, the aliens told him that in 60 years there would be an alien born with the genes of an earthling farmer.

In 2003, Zhang took Meng for a lie detector test. He passed. But he failed the hypnosis test, which iced the expectations of UFO enthusiasts, but not of Zhang.

"We can't simply draw conclusions just because he failed a test. This may be beyond our technology and understanding," Zhang said.

Originally from Henan Province, Zhang came to Beijing in 1990 and developed an interest in UFOs while he was studying at Beijing University of Aeronautics & Astronautics, the first Chinese university to focus on astronautical science and technology.

Zhang bought a lot of second-hand UFO magazines and read them religiously during this period. Soon he became obsessed with the mysterious flying saucers.

A few years later, he met his wife at a UFO meeting held in Dalian. Even though she is not a believer in UFOs, he often tells her that it was the aliens that brought them together.

He joined the Beijing UFO Research Association in 1992 and started doing his own investigations."Not every report is worth investigating," he said. "Some are real, some are fake, and some are just unclear."

The number of people in China who believe in UFOs is rising. Registered UFO associations all over the country have a collective total of about 50,000 members.

To advance his time-consuming and money-burning research, he set up Flying Saucer Advertising company in 2000. However, his employees did not likely see their boss often, as Zhang had to devote most of his time and energy to his "real career."

Over the years, he has spent over 100,000 yuan (nearly $16,000) on investigating UFO cases, including so-called alien abductions.

Alien devotion

Zhang said he believes God is an alien. The concept comes from a recent investigation of an "alien research station" allegedly built by a self-described "earthling agent" in Mayang, Hunan Province. He met this self-claimed earthling agent, a 80-year-old veteran named Xiang Kuansong, in October.

According to Xiang, two aliens visited him in the late 1980s. They lived with him for three years and asked him to build an alien research station for them to use as their dwelling place when they come to visit Earth next time. Following their design, the old man spent 17 years building the station on his own. The project was completed in late 2011.

To prove that Xiang is telling the truth, Zhang turned to Wu Yali, a psychic who he said understands alien languages, to "communicate" with these aliens in early November. After observing a picture of Xiang and his station, Wu told him the case is worth deeper investigation.

"She told me I need to be patient and hasn't told me the whole story yet," Zhang said. "And more importantly, they [the aliens] are going to visit me soon."

Back in 1968, Swiss crank Erich von Daniken claimed in his book Chariots of the Gods? Unsolved Mysteries of the Past that aliens brought religion and technology to Earth.

Zhang brought this hypothesis to China. Through his research, Zhang said he believes Mayang is connected to the Mayan ruins because the words sound similar. Also, he insists that aliens are from Venus because Venus has often been called Earth's "sister planet," and the alien told Xiang that earthlings and aliens are as close as brothers.

Zhang gave a brief report on the case of Xiang's alien station to UFO associations in Hong Kong and Shanghai in June, and continues to blog about his investigations. Many UFO enthusiasts find his work fascinating and want to assist with the investigation.

Despite all his research, Zhang has never met an alien in person. He paid a visit to a psychic earlier this month to make contact with aliens and was told they wanted him to continue his research, as Xiang hasn't told him the whole story yet.

When asked what he will say to the aliens if they really do show up, he said, "I will ask what can I do for them."