However, the police's chargesheet, whichlays out the evidence against the suspects, does not mention who hired them, or why.
Four people - three private detectives and a constable - have been arrested. Among them, is Anurag Singh, who had been arrested in 2005 for tapping the phone of former Samajwadi Party leader Amar Singh .
The espionage was exposed when the constable, Arvind Dabas, was caught using a senior officer's email account to request a telecom company to share Mr Jaitley's records.
The investigation since then has allegedly revealed that cell phone details for 52 different people, most of them high-profile politicians or businessmen, were accessed by the gang.
The police say the suspects swapped information and mobile phone records through email accounts that they accessed using the same password. The men would reportedly store the information as a draft email. Later, that would make it tough for the police to collect details, because no emails had actually been sent.
While the people who hired or organised the espionage have not been identified, the police will for now focus on Anurag Singh. They say that as the ring-leader, he planned to use cellphone details to eventually black-mail the victims.
The police have also not been able to establish any payments to or within the group.