UPDATE, 16 Dec 2015: The Mumbai police is hoping to solve the murder case of installation artist Hema Upadhyay and her lawyer Harish Bhambani with the information provided by her husband Chinatn Upadhyay.
"Some of the suspects are known to Chintan as he has interacted with them while he was based in Mumbai. Information obtained from Chintan about these people can shed light on how they came into contact with Hema and her interactions with them," The Hindu quoted a police source as saying.
The Mumbai police questioned Chintan in connection with the murders on Sunday and Monday.
The Mumbai police are on the lookout for a metal fabrication artist on whose orders the man arrested from Varanasi allegedly murdered installation artist Hema Upadhyay and her lawyer Harish Bhambani.
Hema and her lawyer were murdered on Friday night and their bodies were recovered on Saturday evening. Their bodies, wrapped in plastic bags, were stuffed into cardboard boxes and dumped in a drain in Kandivali.
A joint team of Uttar Pradesh's Special Task Force (STF) and Mumbai police arrested Shivkumar, the suspect in twin murder case, from near his village in Varanasi on Monday. The Mumbai police had earlier detained three people who allegedly assisted Shivkumar in the murders.
The Mumbai police reportedly said that Shivkumar confessed to killing Hema and Bhambani on the orders of metal fabrication artist Vidyadhar, who claimed that the installation artist owed him some money.
"Shivkumar has claimed that five people were part of the murder conspiracy. Hema had defaulted in making payments and that was the possible reason for killing her," UP Additional DGP Daljit Chowdhary told The Indian Express.
Another police official told the IE that Shivkumar confessed to killing the duo himself on the orders of his "boss". "Seth ke kehane par kiya (I did this on the orders of the boss)... I was not paid by him for this," Shivkumar had said.
The police also recovered 11 bank cards from Shivkumar, of which six belong to Hema and five to her lawyer.
"We have recovered 11 bank cards â€” six belonging to Hema and five belonging to Bhambhani â€” from Shivkumar's Varanasi residence. There are some club house cards which have also been recovered. Chintan's visiting card was also seized from his residence during the searches," he added.
The police are still unsure about the motive behind the murder.
Meanwhile, a Mumbai court has sent three accused in the twin murder case to police custody till 19 December.
The police are also interrogating Hema's estranged husband Chintan Upadhyay after his call records showed that "numerous calls" were shared between him and Vidyadhar around a fortnight before Hema's murder, according to The Indian Express report.
"Vidyadhar's father used to work for Chintan. After his father's death, Vidyadhar worked with Chintan and he was the one who groomed him. The call detail record (CDR) of Chintan's phone shows numerous calls were shared between the two around a fortnight ago. Chintan is not able to explain the calls. Only when we get Vidya will the murder motive be clear," a senior officer said.
In 2010, Chintan had filed for a divorce, which was challenged by Hema in the Bombay High Court in 2013. Hema had sought alimony from Chintan.
However, Chintan claimed that their friends were trying to mediate and help them reconcile.
Upadhyay lived in Mittal Ocean building on Juhu Tara Road in Santacruz (west) and was a well-known artist based in Mumbai. She won awards from the Gujarat Lalit Kala Academy and the national Lalit Kala Academy.
Bhambani was her lawyer since 2013, when she filed a case against her husband Chintan for alleged harassment.