The sessions court here on Thursday convicted Parvez Tak for the 2011 murder of his step-daughter and actor Laila Khan, her mother and Laila's four siblings.
Tak was found guilty of murder and destruction of evidence among other offences under the Indian Penal Code.
The court will hear arguments on the quantum of sentence on May 14.
Tak was the third husband of Selina, Laila's mother.
The actor, her mother and her four siblings were killed at their bungalow at Igatpuri in Nashik district of Maharashtra in February 2011.
The prosecution's case was that Tak first killed Selina after an argument over her properties, and then killed Laila and her four siblings.
The killings came to light a few months later when Tak was arrested by the Jammu and Kashmir police. The decomposed bodies of the victims were recovered from the bungalow later.
The prosecution examined 40 witnesses against Tak.
