CAIRO — Egypt on Wednesday executed nine men suspected of belonging to the Muslim Brotherhood who had been convicted of involvement in the 2015 assassination of the country’s top prosecutor, security officials said.

The nine were found guilty of participating in a bombing that killed the prosecutor, Hisham Barakat, the first assassination of a senior official in Egypt in a quarter-century. Mr. Barakat was also the highest-ranking official assassinated since the military overthrew an elected but divisive Islamist president, Mohamed Morsi, in 2013.

The officials, who spoke on condition of anonymity because they were not authorized to brief the news media, said the families of the men had been told to pick up their bodies from a Cairo morgue.

A total of 15 people have been executed in Egypt since the start of the year. Three were hanged this month for their involvement in the 2014 killing of a judge’s son in the Nile Delta town of Mansura, north of Cairo. Another three were put to death for killing a police officer in Cairo in September 2013. Rights groups denounced the executions, saying the men were sentenced to death after being subjected to torture and beatings to extract confessions.