A former couple from the polygamous community of Bountiful, B.C., has been found guilty of taking a 13-year-old girl into the United States to marry the now imprisoned leader of the sect that practises plural marriage. Justice Paul Pearlman of the B.C. Supreme Court found former husband and wife Brandon Blackmore and Gail Blackmore guilty of the charge of taking a girl across the border for a sexual purpose in 2004. He found James Oler not guilty of the same charge, saying he couldn't prove that the man crossed the border in 2004 with a 15-year-old girl who was later married to a member of the polygamous church. Gail Blackmore leaves the courthouse in Cranbrook, B.C., Friday, Feb. 3, 2017. (Jeff McIntosh/The Canadian Press)

The Blackmores will be sentenced, April 13.

The court in Cranbrook, B.C., heard during their trial late last year about the polygamous beliefs and practices in the Fundamentalist Church of Jesus Christ of Latter-Day Saints.

The three, who are or have been members of the church, are connected to the community of Bountiful in southeastern British Columbia, where the trial heard plural marriage was practised.

Girl married to 60-year-old: records

The charges against the Blackmores centred on records that show the 13-year-old girl was married to Warren Jeffs, the 60-year-old church prophet, now serving a life sentence in Texas.

Oler was accused of bringing the 15-year-old girl across the border to marry James Leroy Johnson, who was 24 at the time of the marriage.

Much of the evidence heard in the judge-only trial came about as a result of a U.S. investigation into Jeffs.

Polygamist leader Warren Jeffs was sentenced to life in prison for sexually assaulting two underage followers he took as brides in what his church deemed "spiritual marriages." (Tony Gutierrez/Associated Press)