Head constable Tilak Raj, under instructions from sub-inspector Anand Dutta, rinsed the girl's purple frock in Hiranakashyap police station till the garment was "dry cleaned", inspector general, Crime Branch, Syed Afhad-ul-Mujtaba, told this reporter.
The two men are among eight people, including special police officers Deepak Khajuria and Surinder Kumar, who have been arrested so far.
He added that within the first 15 minutes of sustained questioning, Deepak Khajuria, the special police officer accused of raping the victim twice, told the investigating officers of the Crime Branch that he saw head constable Tilak Raj wash the girl's clothes and he had done it on Dutta's instructions.
The investigators found that the minor's clothes were washed inside the police station, a few days after the victim's body was found.
The chargesheet said sub-inspector Anand Dutta and head constable Tilak Raj didn't collect vital evidence, and washed the girl's dress to help the accused.