Syrian forces abducted the brother of an officer who announced his defection in June and handed his body over to his family early on Friday, a rights advocacy group said.
On Thursday the security forces raided the home of Mohammed Harmouche, 74, in the northwestern village of Ibleen where they killed three military defectors, the Syrian Observatory for Human Rights told AFP in Nicosia.
Harmouche was also seized during the raid and "his body was returned to his family overnight after he was abducted," Observatory chief Rami Abdel Rahman said.
The brother, Hussein Harmouche, was the first Syrian army officer to announce his defection.
In a June video widely distributed on the Internet and broadcast on Arab satellite channels, Harmouche, a lieutenant colonel, said he was deserting because he refused to fire on unarmed civilians.
Harmouche was able to escape from the country and is said to head the so-called "Brigade of Free Officers" comprising several reported defectors from army ranks.
On Thursday, the Observatory reported that several army vehicles stormed Ibleen village in the Jabal al-Zawiyah northwestern district and raided Mohammed Harmouche's home in search of people on the wanted list.
Later Abdel Rahman said three defectors were killed and two others arrested.
But Syria's official SANA news agency, quoting an unnamed military source, said the raid targeted several members of "armed terrorist groups."
According to SANA, six members of the security forces were killed and three others wounded in the operation, during which weapons, ammunition and military uniforms were seized.