'It was revealed that Kumar was introduced by Lal Bahadur to the Mahesh Kumar for arranging blood. The guard was also paid Rs.200 for the deal,' the police officer added.

During questioning it was revealed that Kailash and Mahesh were actively involved in kidney transplant rackets also and were arrested twice during 2004 and 2006 respectively.

Investigation is on to find out whether there was a nexus between the blood bank, hospital administration, security staff and others, or if there is a larger network behind it, police sources said.

'Their involvement cannot be ruled out at this stage because all these accused persons were working openly,' the officer further said.

The police are also scrutinizing blood bank records of the hospital.

The police have so far recovered filled and unfilled blood donation forms of Safdarjung Hospital, three mobile hand sets with 'important' telephone numbers and several diaries containing details of professional donors, clients and other hospital authorities.