A man stabbed and killed his mother and father accusing them of making his pet dog sick. He pleaded guilty at the Old Bailey, London on Thursday, Oct. 3.

The man surrendered himself after calling the police on May 23. The police identified the suspect as Sergey Koudriavstev, a 48-year-old man who had moved in with his parents, 68-year-old Tatiana and 69-year-old Vladimir Koudriavstev, three years ago. They originally came from Russia but have been staying in London for a long time.

According to a police statement, the man confessed that he killed both his parents in an apartment in Appleford Road, Ladbroke Groove, West London. He made the call from Surrey where the officers found him in a churchyard area and arrested him for two counts of murder. Other officers rushed to the spot at Ladbroke Groove after the tip-off and found the dead bodies of Tatiana and Vladimir. The post-mortem reports suggested that the couple died as a result of stab wounds.

Sergey was detained for further investigation and revealed during an interview that he had moved into his parents’ house with his Nepolian Mastiff named Enzo. He alleged that both his parents would leave the windows open and cause a "drought-like situation" for the old dog which was harming the pet.

As a result of their behavior toward the dog, Sergey decided to take the grave step. On the day of the incident, he argued with the couple and then stabbed them to death. He fled the apartment and left his dog at a veterinary clinic. An animal charity found another house for the dog later on.

This image shows a pair of handcuffs at the Commissariat de Police Nationale (National Police Station) in Alfortville, France, Nov. 21, 2016. THOMAS SAMSON/AFP/Getty Images