Georgina Gharsallah, 32, was last seen on March 7 2018, leaving Clifton Food and Wines store in Clifton Road, Worthing - and despite months of investigations, she has yet to be found.
In recent months, Andrea Gharsallah, Georgina's mother, has ramped up her criticisms of how Sussex Police handled the case. This came after the force decided to record her disappearance as a homicide.
She wrote an open letter to Giles York, chief constable of Sussex Police, asking him to explain why certain witnesses had been discounted and more CCTV footage had not been found.
And now, she has called on Priti Patel to step in.
In her change.org petition, Andrea said on behalf of her family: "We ask Sussex Police's investigation and conduct into my daughter Georgina Gharsallah's disappearance to be reviewed by an outside independent body.
"We appeal to Priti Patel, Home Secretary & Member of Parliament UK, to intervene and call for a public enquiry into the failings by Sussex Police regarding the case of Missing Georgina Gharsallah."
The petition has received more than 2,000 signatures so far.
In late December, Sussex Police responded to Andrea's open letter.
Senior Investigating Officer, Detective Chief Inspector Andy Wolstenholme said: “We remain dedicated to investigating the disappearance of Georgina and progressing any credible lines of enquiry.
“Appeals and information about her disappearance have been published not only on our website and social media, but by local media too, and these have included potential sightings and a video appeal from the family and another senior officer.
"We have been able to work with the Missing Persons and Crimetoppers charity, the latter of which are providing a £10,000 reward for information which leads to the discovery of Georgina.
“Despite all of this and all other investigative lines of enquiry to date, we have been unable to find any proof that Georgina is alive and the case was re-classified as a homicide in August this year. We are committed to recording suspected crimes fairly, openly and accurately and following a number of vital enquiries to test ‘proof of life’ were unable to conclusively show that Georgina is alive, I took the decision to record her disappearance as homicide.
“This will undoubtedly be an extremely difficult time of year for the family and friends of Georgina, who continue to wait for answers they desperately need.
“We know someone must know something as it is simply impossible for someone to disappear without a trace. If you have any information which you believe could assist us in our investigation please get in touch with us by going online or calling 101 quoting Operation Pavo. Alternatively, You can also contact the independent charity Crimestoppers anonymously on 0800 555 111 or report it online."