Aligarh Senior Superintendent of Police Akash Kulhary told , "Those arrested on Saturday have been identified as key accused Zahid's brother Mehndi and his wife."
He said they have been charged as co-conspirators in the case.
The police had on June 6 arrested two primary accused, Zahid and Aslam, who they said have confessed to killing the girl after her father failed to return Rs 10,000 he had borrowed from them.
Another police officer related to the probe said that on May 30, Zahid and Aslam abducted the girl from the area after she was returning home from her aunt's home in the evening. They took them to the latter's house and killed her.
Connecting the role of Mehandi and his wife, the police officer said, that they helped them to cover up the crime.
When asked about the case of rape registered against one of the accused, Kulhary said, "One of the accused arrested earlier by the police has been accused of raping his own daughter in 2014."
The SSP said that he was arrested on the complaint of a relative. But he was granted bail some months later.
Kulhary said four cases are pending against him, filed under various sections of rape, assault with intention to outrage modesty of a woman and kidnapping.
The SSP also said that five police officers have been suspended for negligence of duty on the basis of the inquiry conducted by circle officer Pankaj Srivastva.
He further said the police have began proceedings to invoke the stringent National Security Act against the accused.
The incident took place in Tappal town here in Uttar Pradesh. According to reports, the girl's body was found on June 2 in a dumping ground near her home, three days after she went missing.
Her mutilated body was recovered after stray dogs had been spotted carrying what appeared to be human body parts.
( With inputs from IANS )