KOCHI: In a rare instance of a high-ranking police officer being nailed in a fake encounter case, a CBI court in Ernakulam found a former top officer of Kerala police guilty of killing Naxal leader Arikkad Varghese about 40 years ago.Judge B Vijayakumar convicted former IG K Lakshmana under Section 302 (murder) read with section 34 (acting with common intention) of IPC. He would pronounce the sentence on Thursday. The judge, however, acquitted former DGP K P Vijayan, who was also an accused in the case, giving him the benefit of doubt. Varghese, who had struggled for the cause of tribals in Wayanad district of Kerala, was killed in a "police encounter" in the Thirunelli forest on February 18, 1970. The case triggered a major debate in the state and elsewhere for many reasons, apart from the long period it took to reach this conclusive stage.The case took a decisive turn when police constable P Ramachandran Nair made a public admission in 1998, some 28 years after Varghese fell to police bullets, that it was he who had shot Varghese on orders of Lakshmana, then a deputy superintendent of police. Vijayan was a DIG then.Following this, human rights activists sought reopening of the case and Ramachadran Nair himself impleaded in it, seeking a detailed CBI probe. He died in November 2006, but had written an autobiographical account of the killing. The Kerala HC ordered a CBI probe in 1999 into the death of Varghese after his erstwhile comrades filed a petition.