Noel Brown, 69, and Marie Brown, 41, were found in Deptford on Monday.
Police said a link to the 1999 sex attack was an “obvious line of inquiry” but they had no evidence that revenge was the motive for the murders.
They also revealed Mr Brown’s attacker had tried to dismember his body. No arrests have been made.
Police have stepped up patrols in the area following the murders.
The bodies were found after Ms Brown’s family reported her missing when she failed to come home after going to check on her father.
Police said Mr Brown had served a long prison sentence for the sex attack.
Det Supt Paul Monk said there were “no signs of forced entry to the property” and police were trying to establish “if the suspects or suspects were known to Noel and if Marie disturbed them.”
Post-mortem examinations found she and her father died as a result of strangulation.
Det Supt Paul Monk said it was “a deeply distressing time for Noel and Marie’s family as they come to terms with their loss.”
He said Mr Brown was “well known and liked locally” and was last seen alive on 30 November in his local betting shop, Paddy Power, in Deptford High Street.
“There has been speculation that his murder was as a result of a large gambling win, however at this time there is no evidence to suggest this was the case,” he said.