The National Investigation Agency (NIA) will file a charge sheet on Monday in the Pahalgam terror attack case, in which 26 people, mostly tourists, were killed by Pakistan-based terrorists, officials said. NIA investigations had found direct involvement of three terrorists in the April 22 terror attack. The anti-terror probe agency will present a charge sheet before a NIA special court in Jammu on Monday, officials added. In June, the NIA had arrested two men for harbouring the three Pakistan-based terrorists, who were killed by the armed forces in July. The arrested duo -- Parvaiz Ahmad Jothar from Batkote and Bashir Ahmad Jothar from Pahalgam -- disclosed the identities of the three assailants as Pakistani nationals affiliated to the proscribed outfit Lashkar-e-Taiba (LeT). The two men provided food, shelter and logistical support to the terrorists, NIA officials had said. The three LeT terrorists, who were killed in the July 28 encounter code-named 'Operation Mahadev' on the .