Maria Santos Gorrostieta escaped assassination twice before while serving as mayor of Tiquicheo, a small town in the state of Michoacan in southwestern Mexico that has seen some of the country's worst drug-related violence, CNN reported.
The first failed assassination attempt occurred in 2009 when assassins killed Gorrostieta's husband.
She survived a second attempt in January 2010 and remarried in 2011 after finishing her term as mayor.
Last week, Gorrostieta was found dead of an apparent blow to the head.
Deputy Attorney General Marco Aguilera of Michoacan state told CNN investigators were not ruling out any possible motive in her killing.
Initially they were focusing on reconstructing the last 11 months of her life, Aguilera said