According to their plan, the accused invited Dethe and his wife for a party at Byculla on Saturday.
From there, he took the couple to a secluded place near the Aiyappa temple in Thane, where they consumed alcohol.
When Dethe passed out, Kharat smashed his head with a stone. With the help of his friend Vikas Damodar Malave, 30, Kharat put the body in a sack and disposed it of in the park.
The body was found on Monday.
The police are checking whether the wife too was involved in the plot.