A 41-year-old businessman, accused of killing three people in 2015 with poisonous lethal injections, was arrested on Wednesday in Chennai. 

He also tested these injections on stray dogs, investigators told The Times of India.

Police said that S Stephen, the accused, had injected potassium cyanide into his victims. He had learnt about it through the internet and ordered it from Mumbai.

He kept the injection filled with poison in a holder, which replaced the stem of an umbrella. Police told TOI that "The remodelled tip of the umbrella would, when pressed hard against the victim, eject the poison through the syringe.”

He then tested that on stray dogs in Injambakkam where he lived. Using these lethal umbrellas, Stephen’s associates killed his brother-in-law John Philomena on April 19, Sridhar on May 17 and Henry on October 10 last year. They had pushed the lethal umbrellas into the thigh of the victims.

“In all the three incidents, the victims were found dead inside locked houses. The autopsy reports also didn't show any traces of poison,“ a police officer told TOI.