Marilyn Carre was giving evidence at an inquiry investigating claims of abuse in the care system dating back to 1945.
The inquiry also heard Ms Carre describe the Haut de la Garenne children's home as a "barbaric" place.
Ms Carre joined Children's Services in 1977 before becoming a probation officer in 1990.
Ms Carre explained how, while serving as a probation officer, she had visited Les Chenes secure school to see a client who had been locked up and was screaming, apparently coming down from heroin.
She told the inquiry she reported concerns to her superiors and was told a doctor had been called, but weeks later, the girl told Ms Carre she had been in agony and had not seen a doctor.
Ms Carre, whose career took her to most of Jersey's children's homes in the 1970s, 80s and 90s, described Haut de la Garenne as a "barbaric" place by today's standards, where violent teenagers were kept with younger children.
The former social worker also said Morag Jordan, who worked at the home and was later convicted of abuse, was "cold as ice" and added that she used to pin children against walls.
The independent inquiry began in 2014 and Chief Minister Ian Gorst has set a deadline of December 2016 for it to conclude its investigations.
Concerns over the treatment of children at Jersey's care homes were either covered up or ignored, according to a former social worker.