"Praise God that we killed him," he said. "God willing we have finished with his evil forever."
Other regime officials appear to have been kept alive. Activists have distributed videos of the provincial governor, Hassan Jalali; the branch head of the ruling Baath party, Suleiman al-Suleiman; and the deputy chief of military security, Col. Ahmed Abdullah al-Jadou.
All videos appeared authentic and corresponded to other reporting by The Associated Press.
The activist also said rebels had captured some 50 political security officers, who are now in a local prison.
The Syrian government has remained mum on the situation in Raqqa in recent days. It blames the violence in the country on an international conspiracy carried out by terrorists.
Syria's pro-government al-Watan newspaper denied Wednesday that Raqqa had fallen, while naming officials who had been captured. It said army reinforcements had reached the city and quoted a military official as saying the city would be "freed" in a few days.
Also Sunday, some of the fiercest fighting in a year was reported in Baba Amr, the neighborhood in the central city of Homs that stood for rebel defiance earlier in the war but also for the government's ability to strike back. The Syrian military besieged Baba Amr for a month last year, killing hundreds of people before retaking the area.
Rebels and regime troops clashed again Sunday in Baba Amr as the government shelled and bombed, said the Britain-based Syrian Observatory for Human Rights, an activist group. Amateur video showed clouds of smoke above Homs.
In the Damascus suburb of Harasta, a rocket-propelled grenade was fired at a van carrying preschoolers, according to Syrian state TV and a government official. The attack killed one child and wounded nine, said the official, who spoke on condition of anonymity in line with briefing regulations.
As some fighters left to attack the remaining regime bases in the province, others have struggled to run the city's affairs.
The Raqqa activist said the city's market opened Sunday, though most residents have not returned. He said rebels had secured enough flour to reopen bakeries and return bread prices to their pre-war level of about 20 cents a bag from about ten times much, he said.
The city currently has two local councils, each run by lawyers who don't like each other, he said.
The city still has about 80 rebel groups, he said, which make coordination difficult. But he said the Faithful of Raqqa Brigade has led efforts to provide security, posting gunmen at government buildings to stop looters.
In a video posted online, the group announced a hotline that residents can call to request assistance. A call placed to the number by an AP reporter was promptly answered by a brigade member.
Abu Yazan, a leader with the group, said he expects they'll get more calls as civilians return to the city.
"The primary goal is to serve the citizen and nothing more," he said.
Associated Press writer Albert Aji contributed reporting from Damascus, Syria.