"At this time, we remain positive and are keeping the faith that she will return to us safe and sound," Shereé Whitfield tells PEOPLE

Shereé Whitfield is expressing gratitude to fans who have helped spread the word about her missing mother, Thelma Ferguson.

The former Real Housewives of Atlanta star, 50, has been searching for Ferguson ever since the 72-year-old went missing on March 23. She was last seen leaving her home in Sandy Springs, Georgia, to go to the bank.

Whitfield first revealed her mom’s disappearance late Wednesday night. Since then, her plea for Ferguson’s safe return has been shared by fans and news outlets alike, as well as by many of Whitfield’s past Housewives costars.

“We want to thank everyone for the enormous amount of love, support and prayers that my family has received,” Whitfield told PEOPLE in a statement on Friday. “Anyone who knows my mom, Thelma, knows that she is a free spirit who travels often and dances to the beat of her own drum. But, she has never been away this long without communicating with us.”

Whitfield went on to thank the Sandy Springs Police Department “for their help in trying to locate her whereabouts. At this time, we remain positive and are keeping the faith that she will return to us safe and sound.”

“Mom, please just come home to us or let us know that you are okay,” Whitfield begged. “Your grandkids and family are worried sick.”

She posted more words of appreciation to Instagram on Thursday, thanking everyone “from the bottom of my heart! 🙏🏾❤️.”

“I truly appreciate the outpouring of love, support, and prayers for my mother’s safe return home. I know this no doubt will move mountains and bring her home. My family and I are humbly thankful for each and every post, report, notification, text, and phone call. Most importantly, I can’t say this enough, I thank you for your continued prayers. We are continuing to keep the faith and staying positive at this time.”

Sandy Springs police say that Ferguson was seen wearing gray pants and a black shirt and was driving a 2009 Honda Accord, according to the Atlanta Journal Constitution.

Ferguson and Whitfield were close; the reality star’s mom often appeared on RHOA, including a season 10 episode in which they celebrated her 70th birthday with a huge, all-cast disco party.

My mom is my hero; she always worked so hard to provide for me and our family,” Whitfield said at the time in her BravoTV.com blog. “It felt good to be able to do this for her and make this milestone birthday so special for her. She had a smile on her face the entire night!”

Whitfield most recently posted a photo of Ferguson on March 8, in honor of International Women’s Day. Ferguson was seen in the pic posing alongside her daughter and granddaughters, Tierra Fuller and Kaleigh Whitfield

Back in February, Whitfield also shared a photo of her mom when the family attended a sporting event for her son Kairo Whitfield at Morehouse College.

In her first post about Ferguson’s disappearance on Wednesday, the former Bravo star revealed she was “hesitant” to speak out about the situation because she is “pretty private when it comes to my family.”

Whitfield also explained that her mother often takes “personal vacations without letting the family know and we respect that side of her.”

“However, this is the longest she has gone without reaching out to anyone from the family or her friends,” Whitfield said. “Right now we are leaning on God and staying positive and prayerful for her safe return home.”

“HOME is where the HEART is and prayer in numbers work. As we all continue to navigate through these uncertain times, remember the blessing of having each other… Family is everything!” Whitfield continued. “I ask that everyone pray for my mother’s safe return home. And I know that our family will be [eternally] grateful.’

Anyone with information about Ferguson’s whereabouts are urged to contact the Sandy Springs Police Department.