Nitesh, the son, was called for questioning in connection with the murder of Bhardwaj at his farmhouse in south Delhi's Rajokri on March 26, while Swami Pratimanand, who allegedly arranged shooters, is on the run.
Sources said a lawyer was also questioned in connection with the case.
Asked whether Nitesh had been placed under arrest, an official said he was being questioned.
Police sources said a contract of between Rs three to six crore was paid to kill Bhardwaj and Pratimanand had allegedly received Rs two crore.
Also Read
Police also recovered two country-made pistols from a canal in Rohtak which were allegedly used to murder Bhardwaj.
Sources yesterday said the desire to set up an 'ashram' of his own prompted the self-styled guru to allegedly take up the contract to kill Bhardwaj. They said Pratimanand, who was thrown out from some ashrams, wanted to open one of his own as he wanted to establish himself.