CALGARY -- A 64-year-old Calgary man faces rape charges in connection with two alleged sexual assaults on medical workers in Calgary that took place nearly 40 years ago.

According to Calgary Police Service officials, Patrick Zamora was identified as a suspect and charged as a result of significant advancements in DNA science that aided the cold case investigation into two sex assaults that took place in 1981.

A female nursing student was returning to her residence at the Foothills Medical Centre in northwest Calgary in the early morning hours of June 16, 1981, when she was attacked and raped.

The following month, a female lab technician was returning to her vehicle from the hospital on Canada Day 1981 when she was similarly attacked by an unknown offender.

"These offences were investigated extensively in 1981 by detectives in the Sex Crimes Unit with no offender identified in relation to the attacks," said Staff Sgt. Michelle Doyle. "These cases highlight that dedicated investigative work coupled with technological advances can result in new information, leading to charges.

"Even after 40 years, we will not stop investigating cold cases."

On Feb. 11, Zamora was charged with rape as well as rape and choking — charges outlined in the 1981 Criminal Code of Canada, the year the alleged crimes occurred — in connection with the cold case investigation.

In 1983, the laws relating to offences of rape were expunged from Canada's Criminal Code and replaced with offences related to sexual assault.

The accused is scheduled to appear in court on April 1.