The serial killer known only as "BTK" suggests in letters that he was born in 1939, lost his father in World War II (search) and is a railroad buff, authorities said Tuesday as they appealed to the public for clues to his identity.

Police released a summary of personal details provided in recent letters they believe were sent by the killer, including scattered facts about his life since childhood.

The killer — known by the self-coined nickname BTK (search), which stands for "Bind, Torture, Kill" — is linked to eight unsolved homicides that terrorized Wichita between 1974 and 1986. After years of silence, the killer surfaced again messages earlier this year.

"In these letters, he has provided certain background information about himself which he claims is accurate," said Lt. Ken Landwehr, who read a statement to reporters but took no questions.

According to police, BTK claims to have been born in 1939, making the killer either 64 or 65 years old. The statement did not say where he was born or where he lived, but that his family moved frequently and always lived near railroad tracks.

BTK's communications indicate a lifelong fascination with trains, police said.

"If all this is accurate and true, it should help them out a little," Dale Fox, whose 25-year-old daughter, Nancy, was slain in 1977, told The Associated Press.

While Fox said it was hard to hear the details, "I feel like this guy is wanting to be caught, the way it sounds to me."

Attention has refocused on BTK since March, when The Wichita Eagle (search) received a letter with information on an unsolved 1986 killing. The letter contained a copy of the victim's driver's license and photos of her body.

It was the first communication from the killer since the late 1970s, and police said it linked the serial killer to the 1986 slaying. The other seven slayings were in the 1970s, with BTK claiming responsibility for those deaths in letters to the Eagle and a television station.

Police have received thousands of tips from the public since March.

Among other details provided by police:

BTK's father was killed in World War II, and he was raised by his mother, with his grandparents caring for him while she was at work. When he was about 11, his mother began dating a railroad detective.

His grandfather played the fiddle and died of lung disease.

BTK's communications include accounts of a cousin named Susan who moved to Missouri, and of a woman he knew named Petra who had a younger sister named Tina.

In the early 1950s, BTK built and operated a ham radio. He participated in outdoor activities such as fishing and hunting, attended church and went to a military school. He served in an unspecified branch of the military and was discharged in 1966.

BTK has shown a basic knowledge of photography, including the ability to develop and print pictures. Police said that according to his messages, his first job was as an electro-mechanic, and after more schooling he repaired business equipment.