Police were questioning family members of five attackers who stormed an upscale restaurant in Dhaka’s diplomatic zone and killed police officers and hostages before they were fatally shot by security forces over the weekend, an officer said on Wednesday.

The police officer said parents and relatives of the five men were questioned on Tuesday and some again on Wednesday. The officer declined to give details and spoke on condition of anonymity as he was not authorized to talk to reporters. The officer also said authorities have freed three of five former hostages they had been holding for questioning, reports the Press Trust of India.

Authorities were looking into the backgrounds of these people and questioning their families and friends. Police have eight people in custody, including one described as an attacker, but no one has been arrested as a suspect.

Two police officers and 20 hostages including nine Italians, seven Japanese, an Indian and three students at American universities were killed. Thirteen hostages were rescued when security forces stormed the restaurant Saturday morning. Authorities said security forces, civilians and some hostages were injured but have not given details.

Meanwhile, Imtiaz Khan Babul, a politician in the ruling Awami League party whose son Rohan Imtiaz was one of the Bangladeshi attackers, said many other young Bangladeshi men have been missing like his son was for several months before carrying out the attack.

Babul told The Associated Press that the missing men are from educated families and are sons of serving and retired government employees.

Babul urged the government to take these cases seriously and give them importance. ‘Those who have recruited them have done it with a target,’ referring to their family backgrounds.

‘Their (parents) are not speaking to the media, fearing their sons might be killed, leaving them in great torment.’ He said his son had not changed his behaviour notably or become more religious before he went missing in December.

‘It did not happen that all of a sudden he changed himself. He did not start going to the mosque suddenly,’ he said. He noted that his son’s room was not islated but was near the rooms of the rest of his family. ‘We often visited his room, but did not find any (religious) books. We did not see any souvenirs magazines or related Islamic books,’ he said.