A woman who bit off part of a man’s tongue during an alleged sexual assault more than 60 years ago has received a formal apology from South Korean prosecutors, as they sought her acquittal during a retrial after decades of living as a convicted criminal.

Choi Mal-ja, now 80, was 18 when she bit the tongue of a 21-year-old man who she said was attempting to rape her in Busan, South Korea.

She was convicted of “aggravated bodily injury” for biting off 1.5cm of his tongue in self-defence and sentenced to 10 months in prison, suspended for two years. Her alleged attacker received a lighter sentence for trespassing and intimidation after prosecutors dropped the attempted rape charges against him.

“The prosecution failed in its role and went in the opposite direction,” he said. “We caused immeasurable pain and suffering to Ms Choi Mal-ja, who should have been protected as a sexual violence victim. We deeply apologise.”

During proceedings, the prosecution asked the court to clear her of the past conviction.

After the hearing, Choi emerged from Busan district court with her fist raised, shouting three times: “We won!”