Özkan Zengin was born in 1982 in Istanbul, Turkey. Unmarried, he worked as a baker. Details about his early life are limited, but it is known that he began his series of murders in May 2008, targeting gay men in the Kartal district of Istanbul.

Between May and July 2008, Zengin committed a series of murders targeting gay men. His modus operandi involved meeting his victims in public areas, consuming alcohol together, and then moving to secluded locations under the pretense of engaging in sexual activity. Once isolated, he would attack, often attempting to slit the victim's throat. If this did not result in immediate death, he would bludgeon them with nearby objects before disposing of their bodies in wells or cesspools near the crime scenes. In one instance, he buried a victim alive.​

Mehmet Naci Zeyrek (30): Murdered on May 28, 2008. Met Zengin in a park in Kartal; after drinking together, they went to a wooded area near an abandoned cement factory where Zeyrek was killed and his body disposed of in a septic pit.​
Ercan Coşkun: Attacked and robbed on June 27, 2008, while relaxing on the beach during a day off from his baking job. Zengin fled the scene when people approached, leaving Coşkun's body behind.​
Yaşar Mızrak (44): Murdered on July 19, 2008. Encountered Zengin at a beach in Kartal; lured to the same wooded area and killed in a similar manner, with his body also placed in the septic pit.​
Enes Arıcı (25): Murdered on July 28, 2008. Met Zengin while drinking on the beach; taken to the abandoned cement factory area, attacked, and thrown into the septic pit while still alive.​

Zengin also confessed to the murders of Aziz Taşdemir and Tarık Güzeller, though their bodies were not recovered alongside the others.​ On August 5, 2008, children playing near the abandoned cement factory detected a foul odor and discovered the bodies in the septic pit. This led to a police investigation. Zengin became a suspect after authorities linked him to recent public disturbances and observed his repeated visits to the crime scene area. He was apprehended on November 20, 2008, in Taksim Gezi Park and subsequently confessed to the murders.​

Zengin was charged with multiple counts of murder and robbery. He was convicted in 2009 and received life imprisonment sentences for each count.​ He referred to the well where he disposed of his victims as his "piggy bank," indicating a sense of control or possession over the crime scene. His case has been documented in various sources, including Sevinç Yavuz's "Turkish Serial Killers," and has been covered in Turkish media outlets.