The prosecution case was that Dharmaraj had in 2010 went to the house of Chitra in Soondi near here and proposed marriage with her.
As she rejected the offer, he attacked her with some lethal weapons resulting her death.
When Chandra's sister Vijayakala reached there with her kid, Dharmaraja fatally stabbed them also.
Delivering the judgement, District Court Judge G P Ilangovan sentenced Dharmaraj for three life terms for the murders, which would run concurrently, and imposed a fine of Rs 15,000.