Kolkata, May 20 : The Central Bureau of Investigation (CBI) has ordered the closure of all the four Special Investigation Units (SIUs) that it started in West Bengal in 2021 to probe the cases of violence following the state Assembly polls in 2021. An order for the closure of the SIUs was issued by the CBI's Deputy Director (Administration), Antoo T. Mathew. A copy of the said office order is available with IANS. The investigating officers deputed in the four SIUs have been asked to submit the case-related documents to the agency's Special Crime Branch (SCB) office at the Central Government Office (CGO) complex in Salt Lake, Kolkata. The officers have also been asked to report back to the respective units from where they initially came. However, the CBI has not revealed the reason for the closure of the SIUs. After the results of 2021 West Bengal Assembly elections were announced, several incidents of violence were reported from different areas of West Bengal, including the state capital of Kolkata. A team of the National Human Rights Commission (NHRC) had visited Kolkata in the wake of the incidents and reported on the authenticity of allegations of unleashing violence against the ruling Trinamool Congress activists. Later, the CBI started a probe in the matter following an order of the Calcutta High Court. It also made some progress on this count by arresting some accused in the case, though it could not trace a number of other accused persons who are still absconding. CBI sleuths have questioned a couple of top Trinamool Congress MLAs in connection, including veteran party MLA Paresh Paul and Birbhum district president Anubrata Mondal, who is currently in judicial custody in Tihar Jail for his alleged association with the multi-crore cattle smuggling case in West Bengal. /IANS