The slaying of a Canadian woman in Hatfield, England, has prompted a police hunt for her ex-partner.

Angela Hoyt, 34, born in Windsor, Ont., was found strangled in her home north of London on Tuesday, Hertfordshire police said.

Police are searching for Martin Collett, 35, the on-again, off-again boyfriend of Hoyt, who had just returned from an assignment in Pakistan with the International Red Cross.

"She was supposed to call us and tell us how it went," her identical twin sister Ami Watanabe told CBC News in an exclusive interview. "We were immensely worried. I knew something was wrong. Call it twin instinct. I know my sister."

Hoyt was found dead in the home she had purchased a year earlier.

She moved to the U.K. in 1999 to travel and play rugby, her family said in a statement. She studied journalism at the University of Wales and worked in media and communications, joining the Red Cross in February 2008.

Canadian Angela Hoyt was found slain in her home on Tuesday, in Hatfield, north of London. Hertfordshire Constabulary

According to Hoyt's sister Ami, Collett "had a temper. He had a terrible temper. And we warned her," she said. "But she just thought she could handle it. She thought she could handle anything."

Collett had hacked and defaced Hoyt's Facebook account. "She was going to go to the police to get a restraining order," said Ami.

"She was a beautiful, lovely girl, happy, excited, Canadian girl in London, working her dream job. Devastated. We're all devastated."

Nick Young, the chief executive of British Red Cross, said: "Angela was a passionate, committed and hugely popular member of the Red Cross family. Her enthusiasm and dedication rubbed off on everyone who knew her.

"Angela's death is a huge blow to us both personally and professionally, our condolences go out to her family, friends and colleagues.

"Our lives have all been richer for having known her."

With report from Nil Koksal