William Unek was born around 1929 in the region now known as Uganda. He worked as a police constable, a job that required him to protect and serve his community. Not much more is known about his early life, family background, or education. As a member of the police force, Unek held a position of authority and was presumably trained in basic law enforcement and firearm handling.

William Unek committed two separate mass murders, one in 1954 and another in 1957, killing a total of 57 people across two countries.

The first massacre occurred in 1954 in a rural area near Mahagi, then part of the Belgian Congo. Armed with an axe, Unek brutally killed 21 people within approximately 90 minutes. The victims were civilians, and the killings appeared indiscriminate. The motive for this first spree was never fully understood, and Unek managed to flee the scene without being captured. He eventually crossed into the British-administered Tanganyika Territory (now Tanzania), where he resumed work as a police officer under a new identity or possibly without his past being discovered.

Three years later, on February 11, 1957, Unek began his second, even more violent killing spree in Malampaka village, Tanganyika, after an argument with his boss. This time he had a stolen Lee-Enfield rifle, ammunition, and an axe. Over 12 hours, he killed a total of 36 people, including his wife and the wife of a police sergeant. He shot many victims, used an axe on others, set a home on fire killing women and children, stabbed someone, and strangled a young girl.

A massive manhunt followed, involving local tribesmen, police, and military. Despite a reward and extensive searches, Unek managed to hide for nine days. Eventually, on February 20, 1957, Unek went to a house near Malampaka seeking food. The homeowner, Iyumbu ben Ikumbu, alerted the police and stalled Unek until authorities arrived. When police tried to arrest him, they threw a smoke bomb into the house, causing a fire. Unek was badly burned while trying to escape and died later that day at Mwanza Hospital.

For his bravery in helping capture Unek, Iyumbu ben Ikumbu received a reward and was awarded the British Empire Medal.