Police reveal two key theories behind Aussie mum Tahnee Shanks' shock disappearance in Mexico

She and her former partner Jorge Estudillo haven't been seen or heard from since May 2, the same day their two-year-old daughter, Adelynn, was found alone outside a Cancun church. 

While Adelynn is now safe in the hands of family in Australia, police still have no answers as to the whereabouts of her parents but revealed to 60 Minutes their two main lines of inquiry.

The first is that Shanks is the victim of domestic violence and Estudillo is now in hiding or on the run.

The second, considered more likely, is that Estudillo is a criminal with links to Mexico's infamous cartels and the couple's disappearance is payback for his dirty dealing. 

"He had been threatened before and he even had hired a bodyguard because he had been threatened before and he was afraid for his life," State Attorney-General Oscar Montes de Oca Rosales said.

"According to the law, we consider them as alive and that's the way that we look for them until something is shown to be different." 

By analysing mobile phone data, surveillance footage and licence recognition technology, investigators have now been able to piece together the couple's bewildering last moments.

Here's what they know so far.

The months prior

Six months ago, Australian Shanks discovered her partner, Mexican-born Estudillo, was having an affair. 

Shanks told her family in Australia she was coming to visit in June to introduce them to Adelynn, but according to her friend Nikita Weller, Shanks had a secret plan to move them there permanently.

"She found out he was into some shady stuff. She didn't say what. But it scared her enough to want to come home," Weller told reporter Tara Brown. 

Shanks later sent a disturbing text message to another friend asking them to remember the name Jorge Luis Aguirre Estudillo.

"Just in case anything happens to me. Make sure you tell them he's a criminal," she said.

Sunday, May 1

Shanks, Estudillo and Adelynn travelled from their home of Merida and checked into a Cancun hotel.

Monday, May 2

Morning

The family were seen checking out of their hotel before leaving town, with CCTV capturing their car leaving Cancun and heading back towards Merida about 11.30am.

11.45am-12pm

After travelling nearly 20 kilometres, their car did a U-turn and headed back towards Cancun, before taking a detour off the highway. The last time a phone signal was picked up from the car was just after midday, as it drove past a supermarket.

9pm

Adelynn was found barefoot outside the Parroquia San Miguel Arcangel Church, one of Cancun's largest, with her parents nowhere to be found. 

Witness Carlos Canto, who was inside the church with family, said a concerned stranger approached him about the little girl before saying he would look for her parents. He never returned.

Canto and his family eventually called police and photos of Adelynn were posted on Facebook, going viral around the world. 

Later that night

Shanks and Estudillo's car was found burnt out in Puerto Morelos, about 40 kilometres south of Cancun. 

Friday, May 6

After recognising Adelynn in photos posted online days earlier, Shanks' mother, Leanne, and brother, Ben, made a mercy dash to Mexico.

Thanks to COVID-19, it was only the second time two-year-old Adelynn met her grandmother and the first time she met her uncle. 

"We were worried about someone else grabbing her, you know? We just wanted her back home, back with us," Ben Shanks said.

Saturday, May 7

Adelynn was released from a refuge for orphaned children into her family's custody and was granted an emergency Australian passport. 

Monday, May 10

Leanne and Ben Shanks arrived back in Australia with Adelynn in tow, taking her home to meet her family in Mackay, who gave the two-year-old a hero's welcome.