You feel like he's on a solo mission," Tania Daou-Alam, who lost her husband in the blast, told Reuters.
Bitar went on to file his own charges against several top politicians, including former ministers allied to Hezbollah.
Bitar, a devout Catholic from Akkar region of the north, has charged officials from across the sectarian spectrum including Shi'ites, Sunnis and Christians.
"I said from the start 'the right person is in the right place'," he added, describing Bitar as just with no political affiliations.
William Noun, who lost his brother in the blast, said of Bitar's move: "This is very much a judicial uprising".