rebecca sedwick took her life in september 2013 and her family and authorities said she had been the victim of online bullying .
a month later , the polk county sheriff 's office said she died after ` malicious harassment ' from katelyn roman , 12 , and guadalupe shaw , 13 .
but the charges were dropped as they found no evidence of messages .
now the youngest girl 's family has filed a lawsuit accusing the sheriff and a deputy of using rebecca 's death as an ` opportunity for media attention '
the sheriff 's office said the claims have ` no merit '