Three people were charged in relation to explosions at a hazardous waste management plant that killed a worker, Niagara regional police say.

Emergency crews were called to Ssonix Products in the early hours of Jan. 12, 2023, in the wake of a series of explosions and a fire. The explosions triggered the evacuation of nearby homes as crews worked to put out the fire.

Ryan Konkin, 37, the only person in the building at the time, was taken to hospital and later died of his injuries.

As a result of a "continued joint investigation" by police, Ontario's Office of the Fire Marshal, the local fire department, the Ministry of Labour, the Ministry of Environment and Ontario Provincial Police, the three people were charged with "criminal negligence causing death" and "arson by negligence," according to a police news release Monday.

The company's website said its line of business includes producing gasoline, kerosene, distillate fuel oils, residual fuel oils and lubricants.

In September last year, Ssonix Products and three directors faced 84 combined charges under the Fire Protection and Prevention Act.

The Ministry of Labour also issued 11 requirements and one order to Ssonix Products early last year.

Orders are issued when a ministry inspector determines a contravention of the Occupational Health and Safety Act. Some examples include clearing debris to prevent trip hazards or protecting workers from electrical hazards.

Requirements are orders issued when an inspector has to get information or verify compliance. Examples of those include a requirement to provide documents or to keep employees away from the scene.

Konkin's fiancée, Natalia Sepúlveda-Lastra, has described him as hilarious and a "hard worker." She told CBC Hamilton last year that first responders who treated him heard his final words.

"He managed to say to the nurses, 'All I did was open the door.' ... I wish I could've been the one that heard that," she said in March last year.