French police on Friday extended the remand the mother and brother of the self-proclaimed al-Qaeda terrorist who killed seven people in France before being shot dead at the end of a 32-hour standoff with police.

According to officials the girlfriend of 24-year old Mohamed Merah’s brother was also kept in detention. All three were detained on Wednesday as police surrounded Merah in his apartment in the southwestern city of Toulouse.

Police and prosecution officials say Merah’s brother, Abdelkader Merah, is himself a radical Islamist, and that traces of what could be an explosive material were found in his car.

Earlier in the week, prosecutors said the first murder in Merah’s spree was committed after he contacted his victim, a 30-year-old non-commissioned army officer, using his mother’s computer.

The detainees are subject to an inquiry on suspicion of terrorism related offence and can thus be held for four days for questioning without charge. Their detention will expire early Sunday.

Monday’s Otzar Hatorah shooting – the third deadly shooting carried out by Merah since March 11 – resulted in the deaths of Rabbi Jonathan Sandler, 30, his sons Arieh, 5, and Gabriel, 3, and 8-year-old Myriam Monsenego, daughter of the school’s principal.

The two previous shootings resulted in the deaths of three French paratroopers. French press reported the slain paratroopers were all – like Merah – of Arab extraction.

Paris prosecutor Francois Molins said Merah told police negotiators during the siege he had “no regrets, except not having more time to kill more people.”

Merah also told police he carried out the murders “to avenge the deaths of Palestinian children” and because of “the French army’s involvement in Afghanistan.”

Meanwhile, officials on Friday sought to defend France’s security services as criticism mounts following revelations that Merah was on both French and American terror watch lists.