Diogo Alves was born around 1810 in Galicia, a region in northwestern Spain. Very little is known about his upbringing or childhood, but by the late 1830s, he had migrated to Lisbon, the capital of Portugal. He found employment as a coachman and lived a relatively obscure life on the fringes of Lisbon's working class.

During this time, he became romantically involved with an innkeeper named Gertrudes Maria, also known by the nickname "Parreirinha." The couple's relationship was unstable, and they were said to have lived together intermittently. 

Diogo Alves’s known criminal acts culminated in a brutal robbery-murder that occurred in Lisbon in the latter half of 1839. The event, which led to his arrest, conviction, and eventual execution, shocked Portuguese society and laid the foundation for the mythos that would later surround his name.

At the time of the crime, Alves had become acquainted with a household that fell under the medical care of Dr. Pedro de Andrade. This family consisted of Maria da Conceição Correia Mourão and her three children: José Elias and his sisters Emília and Vicência. Also present in the household was a servant named Manuel Alves (not related to Diogo). For reasons that remain partly unclear but were likely driven by financial desperation, Alves, along with an unnamed accomplice—formulated a plan to rob the household.

According to court records, Alves either gained access to the residence through deception or by exploiting his knowledge of the occupants’ routine. Once inside, the robbery escalated into a massacre. Alves and his accomplice killed all four members of the household: Maria da Conceição and her three children. The murders were carried out in cold blood, though the exact method of killing remains poorly detailed in surviving court documents. It is widely assumed that blunt force or strangulation may have been involved, typical of domestic robberies of the time. The attack was so vicious that it suggested a calculated attempt to leave no witnesses behind.

The final victim, Manuel Alves, was not originally part of the target plan. He was murdered shortly after the robbery, not for any financial gain, but to eliminate a potential witness who might have known of Diogo Alves's involvement or could have provided information to authorities. This fifth killing added a layer of cruelty to the case and solidified Alves’s image in the public as more than just a thief.

The authorities launched a swift investigation, driven by the social standing of the victims and the brutality of the crime. Within days or weeks of the murders, Diogo Alves was apprehended. During his interrogation, Alves denied responsibility at first, but mounting evidence and witness testimony made denial impossible. Eventually, he was formally charged with the five murders and brought to trial.

Alves's trial was held in 1840, and it was closely followed by the press and the general public. The court proceedings centered around the events that took place in the Andrade household. Prosecutors presented witness accounts, circumstantial evidence, and expert testimony to establish his guilt. The trial culminated in a guilty verdict, and Diogo Alves was sentenced to death by hanging. His appeal was unsuccessful, and the sentence was confirmed by the higher courts. On February 19, 1841, Diogo Alves was executed publicly at Cais do Tojo in Lisbon.