Anurag Singh, the alleged main conspirator arrested in connection with the attempt to access call details of BJP leader Arun Jaitley, had unsuccessfully tried to get licence from the country's only recognised private detectives association a couple of years back.
The association said it had rejected the private detective's application as his credentials were not proven.
"Anurag approached us for accreditation sometime after the Amar Singh phone tapping case came to light in 2005-06. We refused him a license as we were not sure about his credentials.
"He had done MBBS and was into the hacking domain. Our association gives license to firms run by ex-security and service personnel and similar proven experts in the intelligence and information gathering domain," president of the Association of Private Detectives of India (APDI), Kunwar Vikram Singh, told PTI.
The APDI conducts full inquiry before inducting a member into the body, he said.
The Delhi Police have arrested Anurag and three others in the case. All four are in judicial custody till March 6.
Singh said the 1,500-odd detective agencies registered under this all-India banner do not indulge in providing Call Data Records (CDRs) to their clients and they refuse if someone approaches them for such service.
We are very clear about what is legal and illegal, he said.
"We will conduct due-diligence, shadow a person, generate humanly gathered information but not CDRs. Also, the CDR never tells you what was discussed between the parties but it is simply a log that tells you that an individual is in touch with how many people. The APDI members are not in the CDR supplying business," he said.
"Such instances bring a bad name to our profession and hence we want that a Bill that is pending to monitor the private agencies involved in detective work should be passed and enacted. This would weed out illegal operatives in this domain," Singh said.
Once passed, the Private Detective Agencies Regulation Bill would make it compulsory for every private detective and the firm to obtain a license from the Union Home ministry.
The Bill was first tabled in Parliament in 2007 but it was returned back to the Union home ministry after the Parliamentary Standing Committee, then headed by BJP leader Sushma Swaraj, raised questions on some of its contents.
Last year, the Union home ministry made some changes in the Bill and it is likely to be introduced during the ongoing Budget session of Parliament.