Police picked up Asit Das (20) of Jagatsinghpur in Bhubaneswar having rounded up Susant Sahu earlier, DCP A N Sinha said.
One of the accused was arrested from a Bhubaneswar-based university hostel, but police refused to spell out anything else, not even if he was a varsity student.
"We suspect that tender-related rivalry could be the cause of the murder. But this is subject to verification," Sinha said.
One mauser pistol and two live bullets were found in the possession of the arrested, who are in their early twenties.
Routray, a native of Madhupatna here in the city was fired at when he was travelling to his work site near Kandarpur where he was constructing a canal road.
"The assailants had followed him on a motorcycle and fired at least two rounds before escaping," the officer said.
One accused Asit had over five criminal cases pending against him in Jagatsinghpur, including the attack on Ali Pingal, a jail warden last month.