Egyptian police have taken DNA samples from four Sinai families as they search for the bombers who killed at least 64 people in the Red Sea resort of Sharm el-Sheikh, security sources said on Wednesday.
Police are trying to match the DNA from the families with the DNA from remains found at the bomb site, on the assumption that some of the bombers were killed.
But Public Prosecutor Maher Abdel Wahed told a news conference that it would take time to have results. "We haven't got to the perpetrators or identified them yet," he said.
The families all live in or around the north Sinai town of el-Arish, reflecting the investigation's focus on a possible link between the Sharm el-Sheikh bombings and similar attacks on resorts frequented by Israelis last October.
Investigators are concentrating on the theory that the bombings were carried out by Egyptian militants, but were not excluding the possibility they received international help, the security officials in Cairo said.
They noted that there has been an increasing number of hard-line Islamists in Sinai who may have formed cells. In previous years, the sparsely populated peninsula saw little militant activity, in contrast to the Nile Valley where the majority of Egyptians live and where an Islamic insurgency took hold in the 1990s, reports Reuters.
According to Arab News, security officials revealed meanwhile that authorities received information about an imminent terror attack in Sharm El-Sheikh days ahead of the bombings. But they believed it would target casinos, so security was increased around those sites, said two officials, speaking on condition of anonymity.
The officials, who have knowledge of the investigation, would not say where the tip came from, but said security had been put on alert in the resort several days before the pre-dawn attacks.