RAWALPINDI - A man allegedly assaulted a 14-year-old mentally retarded son of a poor rickshaw driver sexually in Dhoke Hayyat Ali, Ward 14 at Gujar Khan on Thursday. On complaint of father of victim, the police registered a case against accused and started investigation with no arrest so far. According to details, a man namely Muhammad Sarfraz lodged complaint with officials of Police Station (PS) Gujar Khan stating his 14-year-old son is mentally retarded and studying in Special Education Centre.