Tak, a forest contractor in Jammu and Kashmir with suspected Lashkar-e-Tayiba links, has told his interrogators that he did not like Sheikh's growing proximity to Shelina, Laila's mother.
Tak is the third husband of Shelina.
Sheikh, a local builder, was also questioned by the crime branch in connection with the case of alleged kidnapping of Laila and five other family members, including Shelina.
Sources close to the investigation told PTI that last year when Laila Khan's family was on a vacation at their Igatpuri farmhouse, Shelina told Tak that she was planning to make Sheikh the caretaker of the property.
According to sources, she had also got ready a power of attorney in favour of Sheikh. This, they said, provided the trigger for the alleged killings.
Tak told his interrogators that Laila and other family members were done to death because they had witnessed him killing Shelina.
The investigators had on Tuesday found six skeletons from vthe family farmhouse in Igatpuri town of Nashik district, raising strong suspicion that they could be of the Bollywood actress and her family members who had been missing since February last year.
Tak, after initially claiming that Laila and her family was in Dubai, told the Jammu and Kashmir police, which had arrested him last month in a forgery case, that he had killed them in Maharashtra.