A simple UPI payment at a toll plaza became the crucial clue that helped investigators crack the sensational murder case of Suvendu Adhikari’s personal assistant, leading to the arrest of key accused Raj Singh.The joint operation by Kolkata Police and Uttar Pradesh Police exposed what investigators describe as a professional hit squad with links to Bihar and Purvanchal.Ambush on May 6 night The victim, Chandra Nath Rath, was shot dead in an ambush on the night of May 6 at Madhyamgram in North 24 Parganas district of West Bengal. Masked gunmen allegedly opened fire near the entrance of Rath’s SUV before fleeing in a silver hatchback.Following the murder, a Special Investigation Team (SIT) was constituted. During the probe, police tracked two other suspects, Mayank Raj Mishra and Vicky Maurya from Bihar’s Buxar district, through technical surveillance inputs.Investigators said the assailants had meticulously planned the attack and escape route, but made one critical mistake while fleeing. The accused reportedly used a UPI transaction to pay toll charges at the Balia toll plaza, leaving behind a mobile number that enabled police to trace them.CCTV camerasHigh-definition CCTV cameras installed at the toll plaza also captured visuals of the vehicle and its occupants, providing investigators with key evidence.Police said the accused had attempted to mislead investigators by using cloned number plates on the getaway car. The suspects allegedly copied the registration details of a similar silver hatchback after obtaining its images online, hoping to divert suspicion towards an innocent vehicle owner in North Bengal.However, the digital trail created through the toll payment reportedly exposed the entire operation.Who is Raj Singh, alias ChandanRaj Singh, alias Chandan, a resident of Anand Nagar in Ballia district of Uttar Pradesh, is said to hold a position in a Kshatriya social organisation. Police records indicate he was earlier booked in a 2020 murder case involving an egg trader and was out on bail.He was arrested near Ayodhya while allegedly returning from Lucknow after attending a wedding function. Investigators are also examining his alleged links with criminal networks operating across Bihar and eastern Uttar Pradesh.The arrested suspects have been brought to Kolkata on transit remand. Police are now probing the larger conspiracy behind the killing and trying to identify the mastermind and motive behind targeting Adhikari’s close aide.