Interception of mobile phone calls from Dhanbad jail where Iqbal has been lodged and Ranchi's Hotwar jail where his father Fahim Khan is lodged, led to the detection of a conspiracy to demand extortion or kill railway contractor A K Jha, Deputy Superintendent of Police Amit Kumar said.
While Fahim is serving life sentence in a murder case, his son is an accused of killing a railway contractor in 2013.
The 'contract killer', identified as Rinku Khan alias Amir, was arrested from near Bank More here yesterday. He was allegedly hired by Iqbal to carry out the plan.