Additional District Judge Amar Pal Singh held Pappu, his father Subhash, mother Devi, sister Suman and another relative Shiv Chandra guilty yesterday.
The court also imposed a penalty of Rs 5,000 each on the convicts.
In June last year, Pratibha was set on fire and killed by her husband Pappu and in-laws for dowry in Pal Chandraha village, according to the prosecution.