RCMP officers from British Columbia are heading to Texas next month to dig deeper into allegations of child trafficking.

The investigation was launched after U.S. police found documents that described how leaders of a breakaway Mormon sect shuttled children over the border to be married to much older men.

Three years ago, Texas police said they discovered a hidden vault of records when they raided a compound belonging to the Fundamentalist Church of Jesus Christ of Latter-day Saints.

There were hundreds of boxes that included the dictated diaries of the church's self-proclaimed prophet, Warren Jeffs, and meticulously kept marriage records.

Jeffs is serving a life sentence in a U.S. prison for sexually assaulting two of his child brides, aged 12 and 15.

Affidavits filed by B.C.'s attorney general allege the two leaders of separate FLDS sects in Bountiful, B.C. — Winston Blackmore and James Oler — may have been witnesses at U.S. marriage ceremonies involving child brides, may have provided their own daughters or were married themselves to children.

The RCMP won't divulge who is being investigated, said Cpl. Dan Moskaluk.

"These allegations are historical allegations that occurred in the late '90s upwards to as late as 2006," Moskaluk said.

After months of planning, he said investigators will meet in mid-December with Texas police and prosecutors to interview possible victims and witnesses.

The timing has nothing to do with this week's B.C. Supreme Court decision upholding the ban on polygamy, Moskaluk said.

Some of the documents seized in Texas were submitted as evidence during the B.C. court hearing.

Warren Jeffs, the self-proclaimed prophet of the Fundamentalist Church of Jesus Christ of Latter-day Saints, sits in a Utah courtroom in 2007. Jud Burkett/ReutersA former FLDS member who fled the church and now lives in Washington, Kathleen Mackert, alleges that child trafficking did occur.

"Child brides have been trafficked to Canada for my entire life and before then. As long as I've known, it's been going on," Mackert told CBC News in a telephone interview Friday.

Mackert said that although the progress in the Canadian investigation has been slow, she's hopeful co-operation between authorities in both countries will speed things up.

With files from the CBC's Curt Petrovich