The authorities in Egypt said on Thursday they had identified the second of two jihadist bombers who targeted Coptic Christian Palm Sunday services last week.
The interior ministry made the announcement after President Abdel Fattah al-Sisi pledged as he visited Coptic Pope Tawadros II to hunt down the perpetrators of the bombings.
The Islamic State group claimed the Sunday attacks, which killed 45 people and followed a December 11 suicide bombing that killed 29 in a Cairo church.
Sisi's visit to the papal seat in the capital came a day after the interior ministry identified the bomber who struck outside Saint Mark's church in Alexandria, killing 17 people.
Sunday's first bombing at the Mar Girgis church in Tanta, north of Cairo, killed 28 people.
Sisi said "state agencies were exerting their utmost effort to chase down the perpetrators of those vile acts," the presidency said in a statement.
On Wednesday, the interior ministry identified the perpetrator of the Alexandria attack as Mahmud Hassan Mubarak Abdullah, born in the southern province of Qena in 1986.
On Thursday, it said it had now also identified the bomber who blew himself up in the Tanta church.
"DNA tests carried out on the family of a fugitive member and the remains of the suicide bomber... made it possible to identify him as Mamduh Amin Mohammed Baghdadi, born in 1977 in Qena province, where he lived," it said.
The ministry said he was a member of a "terrorist" cell, and also announced the arrest of three other members of the group.
On Wednesday, it also offered a 100,000 pound (about $5,500) reward for information leading to the arrest of suspects it said belonged to jihadist cells linked to the church attacks.
On Thursday, the reward was increased to 500,000 pounds.
Sisi declared a three-month state of emergency after the bombings and called in the army to protect "vital" installations around the country.
The Coptic Church said on Wednesday it would cut back Easter celebrations to a single mass after the bombings.
The violence came ahead of Catholic Pope Francis's first visit to Egypt, which a Vatican official said will go ahead as planned on April 28 and 29 despite the attacks.
© 2017 AFP