Teet Härm was born in 1954 and pursued a career in forensic pathology, working at the Karolinska Institutet in Stockholm, Sweden. He was considered a promising professional in his field. Details about his early life, family background, and education are limited in public records. Prior to the events surrounding the Catrine da Costa case, there were no publicly known issues concerning his mental health or behavior.

In 1984, the dismembered remains of 28-year-old Catrine da Costa were discovered in plastic bags in Solna, north of Stockholm. Her head and vital organs were never found, leaving the cause of death undetermined. Teet Härm became a suspect due to circumstantial evidence, including his profession, proximity to the locations where the body parts were found, and alleged associations with sex workers.

In 1985, the wife of general practitioner Thomas Allgén reported to the police that their young daughter had made statements suggesting she witnessed a dismemberment, implicating both Allgén and Härm. Both men were arrested in late 1987 and brought to trial in January 1988.

The first trial ended in a mistrial due to media interference. In the second trial, both Härm and Allgén were acquitted of murder charges, as the court could not establish that da Costa died under suspicious circumstances. However, the court stated that the defendants had dismembered her body, a crime for which the statute of limitations had expired. Despite their acquittal, both men lost their medical licenses in 1989, a decision upheld on appeal.

Following the trial, Härm lived in near-total isolation, citing threats and public vilification. In a 2024 interview, he expressed hope that da Costa's real killer would be found and maintained his innocence.