The three sisters were sexually abused for years by their stepfather.

They told their mother about the abuse on at least two occasions. She didn't believe them.

This week, the 32-year-old stepfather pleaded guilty in Edmonton Court of Queen's Bench to four sex-related charges. He admitted that between January 2009 and November 2016 he illegally touched the three girls he referred to as his stepdaughters.

The family's story began in 2008, when an American man from Buffalo, N.Y., met an Edmonton woman online.

She was 30 years old then and had four children. He was 22.

Soon after they connected, he offered to move to Edmonton to help take care of the woman's three daughters and one son.

Within months, he began sexually abusing the two older daughters, who were seven and eight years old when he moved in with the family.

The man's name is protected by a temporary publication ban in order to shield the identities of his victims. The man and his common-law wife have had four more children together since he moved to Canada.

The oldest daughter said her stepfather began to sexually assault her when she was nine, according to an agreed statement of facts.

She remembered one particular night when she was 12 and was excited about a junior-high dance the next day. She stayed up late straightening her hair, then heard her stepfather coming down the stairs to her bedroom. She pretended to be asleep.

The girl later told police her stepfather forced himself on her. Afterwards, she said, he thanked her and told her to get some sleep.

She skipped the school dance the next day.

'Their mother did not believe them'

The middle sister eventually told an investigator at the Zebra Child Protection Centre that her stepfather forced himself on her "a lot." The illegal touching began when she was seven.

The three sisters told investigators at the Zebra Child Protection Centre they had been repeatedly sexually abused for years. (CBC)

"She was scared, so just did whatever he wanted so she wouldn't get hurt," according to the agreed statement of facts.

Once, she told a social worker what was happening, and the social worker told her mother.

"She remembers that everyone got mad at her for talking to social workers and blamed her for social workers attending their house," the agreed statement of facts said.

The two older girls shared a bedroom and talked with each other about the sexual abuse. They tried to make sure neither of them was left alone with their stepfather. But the plan was not always successful, and the illegal touching continued.

When they found out their baby sister was also being sexually targeted by the stepfather, they decided to tell their mother.

"Their mother did not believe them and they felt alone," according to the agreed statement of facts.

The sexual abuse continued for another four years.

Only a bad hug that may have been misinterpreted - Victims' mother during police interview

When the mother was interviewed by police years later, she told officers she remembered the conversation with her daughters, but explained that at the time she thought it was "only a bad hug that may have been misinterpreted."

The girls' brother told police his mother put the girls on a "time out" after they revealed they were being sexually assaulted.

As she got older, the middle daughter reacted to the abuse by staying out more with friends, and began drinking, smoking and doing drugs. She moved to a group home when she was 15.

Sentencing set for May

The sexual abuse against the youngest daughter began on the night of her fifth birthday, soon after the stepfather moved in.

He tried to rape the girl when she was eight, and she later reported to police that she had been repeatedly sexually assaulted between the ages of 11 and 13.

The incident that finally led her to disclose the abuse happened in November 2016, when she was 13. One night at about 11 p.m., the accused tried to force himself on her. When she told him to stop, he tried to pull down her pants. She kicked him. Undeterred, he forced himself on her.

Two days after that assault, the girl sent her mother a text message from school.

"Dad raped me," she wrote.

After she got the text, the mother picked her daughter up from school and took her home. Then she confronted her husband at his workplace about the allegation. He admitted he had sexually assaulted his stepdaughter. The couple went to a police station to file a report.

Five days later, the mother called police and told them her husband was "actively talking about leaving the province and fleeing to Ontario."

Investigators convinced the man to turn himself in, and he was charged with sexual assault and sexual interference and taken into custody because he was considered to be a potential flight risk.

He has been in custody ever since.

The man pleaded guilty this week to three counts of unlawful sexual touching and one count of invitation to sexual touching.

The Crown has requested a Gladue report and a forensic assessment for the stepfather.

He is scheduled to be sentenced on May 24.