Colombo, April 25: Police are holding the father of two Sri Lankan suicide bombers on suspicion of aiding and abetting his sons to carry out Easter Sunday attacks that have left at least 359 people dead.Mohamed Yusuf Ibrahim was arrested on Sunday following attacks at hotels and churches. His adult sons, Imsath Ahmed Ibrahim and Ilham Ahmed Ibrahim, blew themselves up in two different attacks earlier that day, reports CNN.On Thursday, police spokesman Ruwan Gunasekera told CNN that their father, Mohamed Yusuf Ibrahim, was in custody on suspicion of aiding and abetting his sons.He added that all other members of the Ibrahim family were believed to be in custody too.Gunasekera told CNN that officers from Sri Lanka's Criminal Investigation Department (CID) and Terrorism Investigation Department (TID) had raided five safe houses in the country over Sunday's attacks.More than 70 suspects have been taken into custody on a range of charges, including suspicion of terrorism, aiding and abetting terrorism and conspiracy to commit terrorism, Gunasekera said.Of those arrested, four suspects are female, and all are Muslims.Gunasekera said most of them were family members and friends of the suspected suicide bombers. None of those arrested were foreigners.Significant raids were carried out on Wednesday night, he added, in which 16 people were arrested at various locations, mostly near the capital Colombo. Three shotguns and two walkie-talkies were also seized.On Thursday, police said search operations were currently underway across Colombo, including the setting up of road blocks. Police have asked the public not to panic.Sri Lanka remains on high alert and numerous controlled demolitions have been carried out of suspicious packages and vehicles in recent days.