The Mamata Banerjee government has challenged the trial court's life imprisonment order against the RG Kar rape-murder case convict in the Calcutta High Court, demanding that he be given the death penalty. Sanjay Roy, a former civic volunteer who worked for the city police, was found guilty and sentenced to life term yesterday by a Sessions Court, with the judge noting the case was not in the "rarest of rare" category for a death penalty. Advocate General Kishore Dutta moved the high court's division bench headed by Justice Debangshu Basak today seeking the death penalty for Roy. The high court has allowed the matter to be filed.