A Sri Lankan spice tycoon, the father of two of the suspected Easter suicide bombers, was arrested Thursday on suspicion of aiding and abetting his sons carry out the deadly terror attacks that left nearly 360 people dead.
Spice merchant Mohamed Yusuf Ibrahim's two sons - identified as Ilham Ahmed Ibrahim and Imsath Ahmed Ibrahim - allegedly detonated their explosives at the Shangri-La and the Cinnamon Grand hotels on Sunday.
Police are holding the brothers' father on suspicion of "aiding and abetting" his sons, the CNN reported.
According to media reports, investigators are also searching the spice trader's mansion in Colombo - which was the site of the eighth blast - for evidence of the attacks. Three police officers were killed in the blast at the mansion.
Elder brother Ilham, who detonated a device at the Cinnamon Grand Hotel, was previously arrested by police and then released, a Sri Lankan government spokesman told CNN.
The majority of the Easter Sunday suicide bombers were from well-to-do Sri Lankan families and they were well-educated, including one who studied in the UK, State Defense Minister Ruwan Wijewardene said Wednesday.
Out of the nine bombers, eight have been identified. The ninth bomber was confirmed as the wife of one of the suicide bombers.
Sri Lanka's government has blamed the attacks on three Catholic churches and three luxury hotels on an Islamist extremist group National Tawheed Jamath (NTJ).
The Islamic State group has claimed responsibility for the attacks, but the government has blamed the NTJ.
Meanwhile, a huge international criminal investigation is ramping up in Sri Lanka, with six foreign police agencies and Interpol assisting local police, including Scotland Yard from the UK and the FBI from the US.
Officers from Sri Lanka's Criminal Investigation Department (CID) and Terrorism Investigation Department (TID) have raided five safe houses across the country in connection with Sunday's attacks.
The Lankan authorities Thursday intensified their raids with the help of the army and arrested 16 more suspects in connection with the attacks, taking the total number of suspects under police custody to 76.
Watch | Isis claims responsibility for Sri Lanka Easter Sunday attacks