SYRACUSE – The sex slavemaster who kept four women chained in a dungeon forced his victims to keep a calendar logging when they’d been raped, when they’d showered and when they’d brushed their teeth, police said yesterday.

Detectives also found an odd, 10-foot-high wooden torture device in the backyard of John Jamelske, the retired handyman accused of raping and enslaving four women in a basement bunker.

Jamelske was arrested last week and is facing kidnapping, rape and sodomy charges.

The weird backyard structure – resembling a cross between a totem pole and crucifix – has a replica of a human skull on top, further confusing investigators.

“We’re trying to figure out what it is,” Sheriff Kevin Walsh told the Post. “It could be just one of the odd, unusual decorating ideas he had.”

Such decorating touches included parts of electronic equipment strewn about, as well as thousands of beer and soda cans on every available surface.

The most disturbing evidence, police said, are calendars where Jamelske forced his victims to document their daily rituals – including when they were raped – as a way of brainwashing them.

“It’s all a part of the way he tried to control the victims,” Walsh said. “There were rituals . . . He had a schedule that he made them stick to.”

District Attorney William Fitzpatrick and Jamelske’s lawyer, Michael Forsyth, also took a first look at the dungeon.

“It’s an extremely frightening place,” Fitzpatrick said. “The sense of isolation a person would have in there is unbelievable.”

Walsh said that the discovery of hundreds of unused overnight envelopes could provide evidence that Jamelske was distributing photos of his victims. They also found unused federal tax forms that included pictures of other missing teens.

Jamelske waived his right to a preliminary hearing yesterday, but Forsyth said, “There’s less here than meets the eye. They haven’t dug up any bodies and it doesn’t look like they’re about to.”

When asked about the chamber of horrors Jamelske in the basement, Forsyth implied it was just a survival shelter.

Police said Jamelske kept at least four women – ranging in age from their early teens to 28 – in his dungeon for up to two years.