The Mumbai Police on Monday achieved a breakthrough in the double-murder case of Hema Upadhyay and her lawyer Harish Bhambhani, as a visiting team of investigators arrested a key suspect Shivkumar Rajbhar, alias Sadhu, at Varanasi in Uttar Pradesh and seized some incriminating evidence linking the suspect to the sensational crime.

Acting on a tip-off from the Mumbai Police, the Special Task Force (STF) of the Uttar Pradesh Police tracked down Sadhu in Varanasi, arrested him and later in the evening handed him over to a visiting team of the Mumbai Police who reached the temple town in the morning.

While the Mumbai Police claimed in the evening that the visiting team of investigators had merely detained not arrested Sadhu, Inspector General (IG) of UP STF Sujit Pande had gone on record saying that they had arrested the key suspect in connection with the twin murders.

With the arrest of Sadhu, the number of suspects who are being questioned in connection with the gruesome crime has gone up to four. The city police had earlier on Sunday detained three persons — Azad Rajbhar, Pradeep Rajbhar and Vijay Rajbhar — in connection with the murders.

Interacting with the media, Sadhu, who hails from Uttar Pradesh, claimed that he had committed the crime on the order of his employer Vidya Vairangi for whom he used to work as craftsman making idols from fibre.

Preliminary investigations have revealed that there were two or more persons behind the ghastly crime that saw perpetrators render Hema and her lawyer Harish unconscious with kerchief doused with some chemical, then kill them, pack them in cardboard boxes and dump their bodies in a drain at Kandivli in north Mumbai.

Given that Sadhu Rajbhar has reportedly confessed to his involvement in the crime, his arrest will make matters easy for the city police in cracking the double case. The UP STF sleuths are also understood to have recovered 11 cards -- bank and club cards belonging to both Hema and Harish --- from Sadhu Rajbhar.

The three detained persons are in the business of manufacturing and selling fibre glass, which was used by Hema and her estranged husband Chintan Upadhyaya, also an artist, for their installations, sources said. All the three detained persons had known both Hema and her estranged husband Chintan.

One of them called up Hema on her mobile phone a couple of hours before her murder on Friday evening. The caller reportedly told Hema that he had some evidence against Chintan to show her. Hema had made it clear to the caller concerned that she would come down to the spot she had been called only if her lawyer accompanied her. Hema had reportedly accompanied her lawyer Harish to the spot where she had been called.

The investigations have revealed that Harish left Matunga residence at 7.30 pm on December 11 (Friday) and reached Hema’s studio at around 8.30 pm. From Hema’s studio, both of them left for some undisclosed spot.

Meanwhile, the Kandivli crime branch sleuths are questioning Chintan Upadhyay, the estranged husband of Hema. After subjecting him one round of questioning on Sunday, the investigators questioned Chintan for better part of the day on Monday.

Sources said that the city police had so far not established any link between Chintan and the double murder. “We have not given him clean chit as yet,” a senior police officer said.

Investigations have revealed that sometime in 2013, Hema had lodged a case under the Indecent Representation of Women (Prohibition) Act, 1986, against her husband Chintan, alleging that he was painting obscene sketches on the walls of her room.

Chintan and Hema, who were classmates at Baroda Faculty of Fine Arts, had married in 1998. After their relations went sour, the couple had filed for divorce in 2010.

Both Hema was a big name in the art circles. Hema used “photography and sculptural installations to explore notions of dislocation and nostalgia”