Their tiny bodies stopped growing, their skin started hanging off their frames and their ribs stuck out from their chests.
On Thursday, a judge at a sentencing hearing heard the details of how the girls were starved and abused. Court heard that although their father didn't physically injure them, he stood by and watched as they suffered.
The smallest of the girls, weighing 13 pounds when she was found by paramedics at the family's home in 2012, later died in hospital.
Her parents had fought for several months in court to keep her on life support, but two Alberta courts agreed that the girl, known as M, should be taken off machines on the evidence of doctors.
Lawyers for the parents applied to the Supreme Court for an emergency stay, but a panel of justices rejected the bid. The girl died soon after.
Doctors have detailed that both twins were deprived of food over a long period of time. They were covered in bruises and had old fractures that had started to heal. An autopsy showed M died of a head injury, combined with starvation.
A Crown prosecutor, calling the circumstances "unfathomable," asked the judge to sentence the father to between 18 and 20 years in prison.
"They should have been able to rely on their father to protect, nurture, feed and love them," Shelley Bykewich argued.
"Starvation of the twins was a choice."
The man, who cannot be named, pleaded guilty earlier this year to manslaughter, aggravated assault and failing to provide the necessaries of life. His wife still faces charges, including second-degree murder, but no trial date has been set.
Bykewich also asked that the man serve half his sentence before he is eligible to apply for parole and that he have no contact with his surviving daughter and her older brother.
The man's defence lawyer asked that the judge take into account his client's guilty plea, the fact he has no criminal record and that he will likely be deported to his native Algeria when he is finished his sentence.
Peter Royal described the man was a hard-working immigrant who came with his wife to Canada in 2008. The couple's three children were all born here.
Royal suggested a sentence of 10 to 12 years would be appropriate. Court of Queen's Bench Justice Sheila Greckol said she will have a decision on June 11.
Royal also read a letter in court written by his client, who said he will never forget his "big mistake."
The father said he feels responsible for everything that happened to the girls and will live with a broken heart for the rest of his life. He offered no explanation for the crime, but said his family found it difficult adjusting to life in Canada.
He wrote that he visited his daughter in hospital before she died, held her in his arms and asked for forgiveness.
"I believe she did. Not because I was a good father. I wasn't. But because she was a perfect daughter."
Court heard police found the couple's four-year-old boy was healthy and had been well cared for. The family's fridge and kitchen cupboards were stocked with food.
There was also evidence that a family doctor saw the girls when they turned one, was concerned about their weight and wanted to see them again. The father never took the twins back, said Bykewich, but he did take his son to the hospital when he had a cut lip.
The surviving twin and boy were placed in foster care after their parents were arrested and have since been adopted.
The girl had to slowly learn to walk and feed herself. It's not yet known what long-term effects she may face, said Bykewich.
What is heart-wrenching, she said, is that the girl will grow up knowing that her father chose to feed and protect her brother, but not her and her sister.