Matti Haapoja was born in 1845 in Isokyrö, a region in the Grand Duchy of Finland. From a young age, he had a knack for getting into trouble, often starting fights and causing disruptions.

As he grew older, Matti's troublesome behavior escalated. He began stealing horses, a more serious crime that marked the start of his criminal career.

In 1874, Matti Haapoja was sentenced to life in prison due to his repeated escapes and continuous thefts. After his final escape, he asked to be exiled to Siberia instead. His request was granted, and in 1880, he was sent to Omsk oblast. While in Siberia, he allegedly killed a man in 1886, which led to his further exile to East Siberia. Though there are stories about him killing two other famous Finnish criminals during this time, these tales lack solid evidence.

By 1889, Haapoja decided to flee Siberia and return to Finland. He claimed he wanted to eventually move to America. To fund his escape, he committed several robberies and murders, likely killing at least three men and participating in another murder. He also obtained a Russian man's passport, whose fate remains unknown.

Haapoja returned to Finland in September 1890. Just a month later, he murdered and robbed a prostitute named Jemina Salo. He was caught in Porvoo a few days later and recognized. At his trial, Haapoja acted arrogantly, confessing to this murder and one he committed in Siberia, hoping for another exile to Siberia. Instead, the court sentenced him to a second life term in prison.

On October 10, 1894, Haapoja attempted to escape from prison again. During this attempt, he killed a guard and injured two others. Realizing he couldn't escape, he tried to kill himself by stabbing, but the wound wasn't fatal. After recovering, Haapoja hanged himself in his cell on January 8, 1895. His skeleton was displayed in the Museum of Crime in Vantaa for many years until he was finally buried in Ylistaro in 1995.

Writer Kaijus Ervasti wrote a book about Matti Haapoja titled "Murhamiehen muotokuva – Matti Haapoja 1845–1895" ("Portrait of a murderer – Matti Haapoja 1845–1895"). 

Haapoja's confirmed victims include farmer Heikki Antinpoika Impponen, stabbed on December 6, 1867, prostitute Maria Jemina Salo, strangled on October 8, 1890, and prison guard Juho Rosted, stabbed on October 10, 1894. He is also suspected of several other murders in Finland and Siberia, but only these can be confirmed with certainty.