Shimla, Sept. 16 -- The Central Bureau of Investigation (CBI) on Monday got the custody of suspended assistant sub-inspector (ASI) Pankaj Sharma for one day for interrogation in connection with investigation into the death of Vimal Negi, chief engineer of the Himachal Pradesh Power Corporation Limited (HPPCL). The ASI has been accused of tampering with evidence (Negi's pen drive). While producing the ASI before chief judicial magistrate Sandeep Singh Sihag, the CBI sought his five-day custody. Speaking to mediapersons, Sharma's counsel Advocate Piyush Verma said the ASI had been cooperating fully with the investigation and there was no justification for his sudden arrest. He said Sharma's wife had already filed a criminal writ petition in the Himachal Pradesh High Court, accusing both the state police and the CBI of keeping her husband under "illegal detention" since the case was transferred to the CBI on May 23. "In that petition, it was alleged that since May 23, when the HC ordered transfer of the case to the CBI, Pankaj Sharma had been kept under surveillance with four police officers deployed round the clock and CCTV cameras monitoring his movements. The HC had on September 5 directed that Sharma be released and allowed free movement, noting that neither the CBI nor the state police required him in the case at that time," Verma said. Vimal Negi, a senior engineer with HPPCL, went missing on March 10 this year and his body was recovered from Govind Sagar Lake in Bilaspur district on March 18. Sharma was the first person to recover his pen drive and other documents and was accused of tampering with the evidence. According to the postmortem report, Negi had died about five days prior to the recovery of his body. The case was transferred to the CBI by the HC on the plea of Kiran Negi, wife of deceased Vimal Negi, who had alleged that her husband was tortured by the superior officers for six months. Negi was forced to work late at night even during illness, she had claimed. Sources said that the CBI had questioned Pankaj several times regarding the allegations that some important data was deleted from the pen drive, which was allegedly formatted....