CAIRO -- Three bearded men approached a university student and his girlfriend during a romantic rendezvous in a park in Suez, and ordered them to separate because they weren't married, according to security officials. An argument broke out, ending with one of the men fatally stabbing the student.
The June 25 attack has alarmed Egyptians concerned that with an Islamist president in office, vigilante groups are feeling emboldened to enforce strict Islamic mores on the streets.
Islamists, including members of onetime violent groups, were empowered after last year's ouster of Hosni Mubarak's secular regime by a popular uprising. They formed political parties and won about 70 percent of parliament seats in elections held some six months ago, although a court dissolved the legislature.
Moderate Muslims along with liberal and women's groups now worry that Mohammed Morsi's presidency will eradicate what is left of Egypt's secular traditions and change the social fabric of the mainly Muslim nation of 82 million people.
Some activists say Islamists already are flexing their muscles in areas outside Cairo and other main cities, taking advantage of the absence of civil society groups and tenuous security in the areas.
They cite reports of efforts to persuade drivers of communal taxis, mostly minibuses that can seat up to 16, to segregate women and men passengers. In some instances, women's hairdressing salons were told to get rid of male employees or be threatened with closure.
"If Islamists are to try and take over the streets and enforce their version of Islam, they will do it in rural areas, at least initially," said Yara Sallam from Nazra, a women's rights group.
The security officials said there was no concrete evidence linking the June 25 killing to radical Islamic groups in Egypt, but it still has stoked fears.
Rights groups say they have sent teams to investigate the Suez killing and establish whether Islamists were behind the attacks.
On the same day, two musicians, who were brothers, were murdered as they were traveling home after performing at a wedding in the Nile Delta province of Sharqiyah, officials said. Radical Muslims consider music "haram" or prohibited, as a distraction from religious duties.
Two ultraconservative Salafi Muslims were arrested, but officials said it was not clear if the killings were religiously motivated.Islamist groups, including Morsi's Muslim Brotherhood and the ultraconservative Salafis, denied any link to the murders.