"We have been looking at this case for over a year, about a year and a half on the (habeas corpus petition) and since early this year on resentencing," Gascón said Wednesday after an event in Sylmar.
Critics have claimed Gascón is using the high-profile case to save his re-election bid.
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Legal expert Lou Shapiro said Gascón's new interest in the Menendez brothers is almost certainly linked to his re-election campaign.
"There is this substantial base out there that does believe that prison systems are overcrowded, that the system over penalizes people, so I think he's trying to tap into that market," Shapiro told Eyewitness News.
Mark Geragos, the brothers' attorney, disputes that claim and says Gascón's office has been interested in their case long before this month.
"Mr. Gascón's office has been engaged with us productively, strongly for well over a year," Geragos said last week at a news conference that featured several of the brothers' relatives calling for their release.
MENENDEZ BROTHERS' CASE: How would resentencing happen?
Lyle and Erik Menendez were sentenced to life in prison for the murder of their parents at their Beverly Hills home in 1989.
There's been renewed interest in the brothers following the recent release of a true-crime drama on Netflix that revisited the murders and trials.
Gascón said earlier this month that his office has taken an interest in possibly requesting that the Menendez brothers be resentenced. He also said his office was reviewing new evidence.
When asked by Eyewitness News Wednesday when he plans to make a decision on the case, Gascón said "probably some time tomorrow or Friday at the latest."
The new evidence presented in a petition includes a letter written by Erik Menendez that his attorneys say corroborates the allegations that he was sexually abused by his father.
Lyle Menendez, who was then 21, and Erik Menendez, then 18, admitted they fatally shot-gunned their entertainment executive father Jose Menendez and their mother, Kitty Menendez, in 1989 but said they feared their parents were about to kill them to prevent the disclosure of the father's long-term sexual molestation of Erik.
Prosecutors at the time contended there was no evidence of any molestation. They said the sons were after their parents' multimillion-dollar estate.
The Associated Press contributed to this report.