Ely Burgos, the mother of Monica Beresford-Redman, said Friday the investigation is taking too long.
Her daughter was found dead in a sewer at an upscale resort in Cancun on April 8.
Mexican investigators have focused on producer Bruce Beresford-Redman, who has not been charged but is barred from leaving the country during the probe.
Authorities say they are awaiting forensic test results.