The trial of a British Columbia religious leader charged with polygamy heard Monday that the accused told police he didn't know a teenage girl's true age when he married her.

Winston Blackmore is the head of a religious group in Bountiful, a community in southeastern B.C. where residents are known for practising a faith that condones plural marriage.

Blackmore is accused of marrying 24 women. James Oler, a former leader in Bountiful, is also on trial and is accused of having four wives.

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In video played at the B.C. Supreme Court trial in Cranbrook, a police officer asks Blackmore about a television appearance where the religious leader admits he married one of his wives when she was 15 years old.

Blackmore responds by saying the girl's parents lied to him, telling him she was 16.

The footage presented by the prosecution shows Blackmore expressing fears about incriminating himself because his lawyer isn't present, but he does not deny practising polygamy.

Many people would be jealous of a family like his, Blackmore tells the officer.

"I am who I am. I've never denied that," he is heard saying in the video.

The polygamy trial began a week ago, hearing from an expert on the history of the Mormon church, who explained how the Utah-based Fundamentalist Church of Jesus Christ of Latter-Day Saints broke away from mainstream Mormonism at the turn of the 20th century.

Both Blackmore and Oler served as bishops for the Bountiful congregation of the so-called FLDS.

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The court also heard last week from a Texas Ranger involved in seizing hundreds of boxes of documents from a ranch owned by the FLDS in 2008.

Dozens of marriage and birth certificates have been entered into evidence at the trial.

The criminal trial has been more than 25 years in the making, with RCMP first investigating allegations that residents of the isolated, religious community were practising plural or "celestial" marriage in the early 1990s.

The trial is being heard by a judge alone and is expected to last at least two weeks. Norma Jean Blackmore, who is Blackmore's first wife and Oler's sister, is expected to testify on Tuesday.