"There have been several loopholes in the investigation. There might be tampering of evidence. The probe should be handed over to the CBI," Aditya's father, Shyamsunder Sachdeva, said.
Aditya's mother, Chand Sachdeva, added: "The perpetrators are influential people and delay may provide them time to swing the case in their favour. We want result in the case before results of Aditya's Class XII exams come out."
Aditya had appeared for the CBSE Class XII examination, results of which are expected this month.
Shyamsunder said cops had touched Rocky's pistol with bare hands - which would have smudged fingerprints - after his arrest.
"The police took possession of our son's blood-stained clothes today, five days after he was killed," the father added. "The clothes were thrown in the campus of Anugrah Narayan Magadh Medical College and Hospital (ANMCH) after the post-mortem on May 8. We brought the clothes home and police took them only after we told them; otherwise they weren't bothered."
The family is also peeved at the state government.
"No administrative official has visited our house," Chand said. "We want chief minister Nitish Kumar to visit our house but he has no time for us. Liquor was recovered from Manorama's house but she is still fugitive. The administration allowed her to escape."
Chand said the police had stopped some of her relatives who were coming to Gaya and even checked the purses of women in the group for liquor, but had not bothered to arrest Manorama after liquor was recovered from her house.
Bindi and Rocky are lodged in Gaya Central Jail. Manorama has been absconding since the JDU suspended her on Tuesday. The cops have procured an arrest warrant against her in the liquor case. She also faces charges of employing child labour.
Teni Yadav, the third accused in Aditya's murder case, is also yet to be nabbed.
The cops raided places in Gaya district today in search of Manorama and Teni, in vain. Patna IG Nayyar Hasnain Khan said police will take Rocky - who is in judicial custody - on remand tomorrow. "The court has granted police remand of 48 hours for Rocky. We will take him on remand on Friday morning," Nayyar said.
Magadh range DIG Saurabh Kumar said: "We are working to collect more evidence so that a strong chargesheet can be filed followed by speedy trial. We will also work to address Aditya's family's grievances."
Aditya's post-mortem report, submitted by Dr P Shekhar of the department of forensic science and toxicology at ANMCH, said the bullet hit him "in the midline on the back of the uppermost part of neck" and the "death was due to injuries of brain and brainstem as a result of firearm fired from a distance of more than three feet."