The killing in May of Chandranath Rath, personal assistant to Suvendu Adhikari, days before he took charge as West Bengal Chief Minister, was the culmination of an alleged conspiracy hatched over six months. The CBI uncovered the plot using digital evidence, including a photo on iCloud, and by joining the dots between CCTV footage, road tolls and multiple phones, including one at the bottom of the Hooghly river, The Indian Express has learnt.The CBI filed a chargesheet before the Additional Chief Judicial Magistrate’s court in Barasat on August 7. The probe, it is learnt, states that the man who allegedly pulled the strings was Sagar Sonkar, Rath’s 29-year-old assistant.Rath was shot inside his vehicle in Madhyamgram in Kolkata around 10 pm on May 6. His associate Buddhadeb Bera was injured in the attack.The chargesheet names 12 people, of whom all but Krishna Kumar Singh (from Bihar) have been apprehended. The arrested include Sagar and his brother Saheb Sonkar (both from Kolkata); Uttar Pradesh residents Vikash Mishra, Vinay Rai, Sanjay Rai, Gyanendra Singh, Raj Kumar Singh, Golu Singh and Naveen Kumar Singh; and Bihar’s Mayank Raj Mishra and Vicky Maurya.There are 585 people listed as witnesses.Sagar and Saheb, 20, were arrested on July 31, more than two months after the CBI held 11 people, including four alleged sharpshooters. The parents of the two brothers told The Indian Express earlier that they did not believe the police charges, as the two worked closely with not just Rath but also Adhikari, in his personal office, and played an active role in Adhikari’s Bhabanipur Assembly seat during the polls.“Sagar was like Chandranath’s shadow. He looked after the financial transactions, even handled payments. Later, he took Saheb along and he too was employed by Chandranath,” said a relative.Hatching of a plotAccording to the CBI probe, Sagar had allegedly come to resent Rath as he saw himself as his equal and believed that getting him out of the way was the only way he could get close to Adhikari. Sometime in November 2025, the probe found, he allegedly “roped in his brother Saheb to procure phones and SIM cards in the names of other persons”.Story continues below this adNext, Sagar allegedly brought in Vikash Mishra, a school friend, who in turn knew Vinay Rai. The CBI claims WhatsApp call records show Sagar and Mishra, a resident of Salempur in Deoria, were in constant touch from January 20, 2026, onwards, allegedly “with the intent to hire contract killers”.On January 30 this year, Vikash Mishra called Vinay Rai over WhatsApp, the probe found. According to the CBI, Rai has criminal antecedents with five criminal cases registered or pending against him, including that of murder. There were more calls between Sagar, Mishra and Rai, investigators said, alleging that on February 6, “in order to arrange the shooters… Vinay Rai contacted his acquaintance, Sanjay Rai, who was at Surat… and asked him to come to Dhanbad immediately”.According to the CBI, after Sanjay Rai came to Dhanbad, Mishra arranged a meeting between him, Vinay Rai and Sagar, where “the modalities for committing the murder were allegedly discussed”.Investigators say this was followed by repeated trips between Dhanbad, Kolkata, Ballia, Ghazipur and other locations.Story continues below this adArrival in KolkataNot long after his meeting with Sagar, Sanjay Rai allegedly arrived in Kolkata and checked into a hotel under the name ‘Pankaj Singh’. The CBI says Sagar paid for his hotel stay and, later, for his accommodation in Salt Lake.On February 18, says the agency, Sagar allegedly took Sanjay Rai on a recce of Madhyamgram, and of Rath’s office, the Assembly and High Court areas. An Uber driver allegedly identified the two. Sanjay Rai went back to Dhanbad the same day, but reportedly came back for reconnaissance in March and April.On April 7, Sanjay Rai, Gyanendra Singh and Raj Kumar Singh visited a vehicle dealer in Patuli (Kolkata) and examined a Maruti Swift, as per CCTV footage procured by the CBI. On April 18, the vehicle was purchased for Rs 3.80 lakh, with CCTV footage and road toll records allegedly showing trips made in it to Dhanbad.The CBI says that the accused also acquired a Nissan Micra and a Hero Super Splendor motorcycle, with the engine and chassis numbers of both obliterated. All the vehicles were subsequently fitted with fake registration plates, as per the agency.Story continues below this adOn May 3, CCTV footage and FASTag records purportedly show the accused travelling from Dhanbad to Kolkata, a distance of 275 km, and then going back via Birati. The next two days, further arrangements were allegedly made, including the preparation of another number plate for the Nissan Micra.The day of the murderThe shooters allegedly travelled to Kolkata from Dhanbad the same day, i.e. May 6. As per the reconstruction, via call-detail records, CCTV footage, and alleged communication between the men, before leaving Dhanbad, they split up.“Krishna Kumar Singh, Gyanendra Singh and Sanjay Rai left for Kolkata in a Swift Car, whereas Mayank Raj Mishra, Vicky Maurya, Golu Singh and Raj Kumar Singh left in Nissan Micra,” the probe says, recording a toll tax payment enroute.The CBI claims that Sagar informed Sanjay Rai of Rath’s location over FaceTime, and that Rai passed the information on to Gyanendra and Krishna.Story continues below this adAs Rath’s car, a Scorpio, entered the Doharia Lane in Madhyamgram, Raj allegedly parked the Nissan Micra across to block it. Then, the probe agency alleges, Krishna and Gyanendra “committed murder of Chandranath Rath and attempted to murder Buddhadeb Bera”.After the shooting, Raj, Krishna and Gyanendra allegedly got onto the Hero Honda Splendor parked nearby, and fled.The motorcycle was found abandoned near the Gouri Kali Bari Bus Stand, and the CBI believes the men allegedly used the Swift next to drive back to Ballia, destroying or disposing of phones and SIM cards along the way.The evidenceThe CBI claims it has mobile tower-dump data from several locations, including Dhanbad, Birati, Jessore Road, Doharia Lane and Barasat Railway Junction, to place the accused there. It also claims evidence that several SIM cards were procured in other people’s names and repeatedly moved between handsets.One significant finding, as per the CBI, was a photograph of Rath on an iCloud account linked to one of the numbers, loaded onto the cloud on March 18, when the phone was at Madhyamgram.Story continues below this adThe CBI claims to have found at least one FaceTime communication between phones allegedly being used by Sagar and Sanjay Rai shortly after the killing, at 10.16 pm on May 6. Another call followed soon after, and the CBI believes Sagar placed it to ascertain Rath’s condition.Ballistic examination showed that two pistols recovered from Naveen were allegedly used to shoot Rath and Bera. Eight firearm injuries were found on Rath’s body, and two bullets recovered.The agency also claims to have found a financial trail, with Rs 30 lakh allegedly handed over on February 24 by Saheb and a friend, Raja Das, to Sanjay Rai at Jamtara, Jharkhand. This was allegedly shared between the accused, with more payments made for vehicles and logistics, as per the CBI.After the murder, around 10.30 pm on May 6, the investigators claim, “Sagar Sonkar handed over an iPhone to Rishabh Sonkar, his cousin, with the direction to dispose of the same… in the Hooghly river… In CCTV footage of Howrah bridge… Rishabh Sonkar is seen throwing something from the bridge at 22.53 hrs.”Story continues below this adThe CBI says that it used divers to try and retrieve the iPhone but was not successful. According to the agency, after the murder, Raj, Gyanendra, Golu, Krishna and Sanjay Rai drove in the Swift to the house of Manoj Rai at Tajpur Manjha village in UP’s Ghazipur, with Krishna getting off at Buxar en route.“At the residence of Manoj Rai, Gyanendra Singh collected the remaining amount, which was kept there for safe custody on 13.03.2026,” investigators say, adding that Manoj got Rs 50,000 for his alleged part in the plot.After this, the CBI claims, Gyanendra, Raj and Golu went to Naveen’s house in Ballia and handed over a bag containing the firearms used in the crime.“Out of Rs 30 lakh, Mannu Singh (Gyanendra) gave Rs 5 lakh to Raj Kumar Singh at the house of Naveen Kumar Singh and dropped him there,” says the agency, adding that Rs 2.85 lakh was later seized from Raj’s father, Tribhuvan Narayan Singh.