Kerala Police arrested Kari Satheesh, the main accused in the Paul George Muthoot murder case, on Tuesday.
He was arrested from his hideout in Alapuzha.
Paul (32), executive director of the Muthoot group, was stabbed to death on Saturday in Alapuzha, 150 km north of Thiruvananthapuram.
The police had earlier ruled out a larger conspiracy behind the murder and attributed it to road rage.
Expressing satisfaction over the progress made by the police, state Home Minister Kodiyeri Balakrishnan said probe was heading in the right direction. Investigators have been able to arrest all accused in 48 hours, he said.