António Luís Costa was born in 1953 in Santa Comba Dão, a small city in Portugal's Viseu district. After completing his education, he joined the National Republican Guard (GNR), serving as a corporal in his hometown for 25 years until his retirement in late 2004. Following his retirement, a series of young women's disappearances occurred in Santa Comba Dão between May 2005 and May 2006.

The unsettling sequence of events began on May 24, 2005, when Isabel Cristina Isidoro disappeared; her body was found in the Atlantic Ocean on May 31, 2005. Later that year, on October 14, 2005, Mariana Lourenço went missing, and her mutilated remains were discovered in June 2006. The third victim, Joana Oliveira, vanished on May 8, 2006; her body was recovered from beneath a bridge based on directions provided by Costa.

Costa was apprehended by the Polícia Judiciária on June 24, 2006. Initially, he confessed to the murders, stating that after consensual sexual relations with the first victim and requesting kisses from the second and third, he suffocated them when they threatened to report him.

He later retracted his confession, accusing an uncle of one of the victims, but wiretapped phone conversations revealed him admitting the crimes to his family. His trial commenced on July 4, 2007, and on July 31, 2007, Costa was convicted of three counts of murder and sentenced to 25 years in prison, the maximum penalty under Portuguese law. He is currently serving his sentence in Évora Prison. ​