Steven Laffin has pleaded guilty to four charges on a sex-trade worker in Halifax. (CBC)

A Dartmouth man accused of killing a prostitute more than two years ago has pleaded guilty to kidnapping and assaulting another sex-trade worker the same year.

Steven Elliot Laffin, 38, pleaded guilty to kidnapping, aggravated assault, uttering threats to cause bodily harm and unlawful confinement on Thursday morning at Nova Scotia Supreme Court in Halifax.

Those charges stem from an incident on Aug. 16, 2010, when a prostitute escaped from the trunk of a moving car on Old Sambro Road in Halifax.

The woman — who told CBC News she has since quit the sex-trade business — told a harrowing story about how she got into Laffin's car and he drove her to a parking lot.

The woman said Laffin grabbed her throat and choked her. She said when she regained consciousness, her mouth was covered in duct tape and her ankles and wrists were bound.

She said she was sexually assaulted, that Laffin slammed her face into the ground and said he would kill her.

The woman said she was stuffed into the trunk of the Laffin's car, but managed to escape and run to a nearby house to call 911.

Laffin was scheduled to stand trial next week before a Supreme Court judge and jury on five charges — including attempted murder — but the Crown said Thursday that charge will be formally withdrawn when Laffin is sentenced in February.

The charge of aggravated sexual assault was also amended to aggravated assault.

Laffin is also charged with second-degree murder in the case of 29-year-old Nadine Taylor, a Halifax woman who disappeared two years ago. His trial on that charge is scheduled to begin in April.