Metropolitan Police working on the disappearance of Madeleine McCann have travelled to Bulgaria to try and find a key witness.
Officers think that "the woman in purple" who has been named by other witnesses could hold some key information into the Madeleine McCann case.
She is believed to be waitress Luisa Todorov, 58, who worked in the tapas bar that the McCanns and their friends visited.
Ms Todorov worked there with her husband Stefan, 50, and is believed to be the woman dressed in purple that two witnesses have reported to police.
WATCH: The night Madeleine was taken, by the Official Find Madeleine Campaign
One witness told police that they saw her standing by a lamppost just outside the McCann's apartment at around 8pm on the day Madeleine went missing, and another saw her about half an hour later nearby.
She and Stefan both gave statements to the police five days after Madeleine's disappearance, both denying any knowledge of what happened to the little girl.
Neither of them have been spoken to since then.
Spanish criminologist Heriberto Janosch González has been working on the case for 10 years, and is sure that Ms Todorov is the one they need to find.
READ MORE | Madeleine McCann timeline: A decade since her disappearance
He said: "I have been combing through all the police files trying to identify who the woman in purple could be.
"It has been widely reported that Yard officers are in Bulgaria.
"Examining all the known statements it seems highly likely the police are seeking the Todorovs. They are the only known people with a clear link to Bulgaria."
Jenny Murat, whose son Robert was the first official suspect in the case but was cleared in 2008, recently spoke about the woman in purple.
She said: "I saw the woman standing on the corner of the street.
"She caught my eye because she was dressed in purple-plum clothes. It struck me as strange.
"It's so usual for anyone, particularly a woman, to be standing alone on the street in our resort, just watching a building.
"The next morning, we heard that a little girl had gone missing, and I later told police about the woman I'd seen right outside. I didn't recognise her and don't have a clue who she is, but she seems a bit suspicious."
This news comes two months after it was confirmed that Operation Grange were granted a further £154,000 by the Home Office to continue their search until next March.
The McCann family's spokesperson, Clarence Mitchell, released a statement on the Official Find Madeleine Campaign Facebook page after the funding was announced.
It read: "Kate and Gerry are extremely thankful to the Metropolitan Police for requesting extra funding.
"They are very encouraged there remains work to be done that requires them seeking an extra budget. They are hoping naturally, it will be granted.
"They are grateful to all those officers who are still working on the case and are actively looking for Madeleine.
"They appreciate everything the police have done and are doing to get a resolution after all this time."
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1 of 11Ferne McCann and Arthur Collins
Ferne might be one of our TOWIE favourites, but the gorgeous Essex girl has been very unlucky in love. Her relationship with Charlie Sims played out spectacularly while she was on TOWIE, and during her time on Celebs Go Dating she never met anyone who she was interested in.However, just days after publically talking about her plans to marry her now-boyfriend Arthur Collins, the police have issued an appeal to find him in connection to an acid attack at a club in London over the bank holiday weekend.
2 of 11Gemma Collins and Stephen Mortimer
Gemma and Stephen had an on-and-off relationship. He spent two years in prison for grievous bodily harm, and during Gemma's stint in Celebrity Big Brother in 2016, he was back in prison for allegedly breaching his license terms.When she left the house, she also had to face rumours that he had cheated on her numerous times.
3 of 11Kerry Katona and George Kay
Kerry and George have had a tumultuous relationship, and although they called it quits in 2015, the couple decided to rekindle their relationship in August 2016.However, during the time of their marriage breakdown George was allegedly detained for assault and unlawful possession of a taser. He also previously served a three-year prison sentence for blackmail.
4 of 11Mel B and Stephen Belafonte
Earlier this year, Mel B filed for divorce from her husband of ten years, Stephen Belafonte. The couple share 5-year-old daughter, Madison, but in the leaked papers Mel cites irreconcilable differences as grounds for divorce.Since then, it has come to light that Mel made many allegations against the film producer, including that he was reportedly physically and verbally abusive throughout their marriage.
5 of 11Lauren Goodger and Joey Morrison
Lauren has received a lot of bad press about the men she has dated. When she first appeared on TOWIE, she had been dating Mark Wright for the best part of eight years before they went their separate ways.Lauren then went on to date Jake McLean for four years, but now she is seeing Joey Morrison. He's a friend of a friend who is currently serving time in prison for violent drugs-related charges, and he is expected to be released later this year.
6 of 11Steph Davis and Jeremy McConnell
Steph and Jeremy had an on-off relationship for the best part of 2016 after meeting in the Celebrity Big Brother house.When Steph announced she was pregnant, Jeremy refused to believe he was the father and throughout the pregnancy she was determined to raise her baby on her own.However, when Caben-Albi was born Jeremy stepped up and appeared to be trying to make up for lost time. The couple reunited, but shortly afterwards reports swirled that Jeremy had been arrested on suspicion of assault.Before the news broke, Steph had shared a picture of her bruised body on Snapchat, prompting fans to believe she may have been the victim. Jeremy denied any wrongdoing and is now in rehab dealing with his demons. Steph has confirmed she'll be there for him when he gets out.
7 of 11Daniella Westbrook and Tom Richards
Daniella and Tom dated cage fighter Tom Richards, and they even got engaged before the relationship broke down in 2015.Following their break-up, Daniella claimed that Tom had violently attacked her although the charges were eventually dropped.
8 of 11Chantelle Houghton and Alex Reid
Chantelle was engaged to Katie Price's ex, Alex Reid, and the former couple share 4-year-old daughter, Dolly.But just weeks after Chantelle gave birth, cage fighter Alex was arrested on suspicion of causing criminal damage to the couple's Brentwood home and the pair split shortly after.
9 of 11Katie Price and Leandro Penna
Katie and Leandro met at an Oscars party in 2011 and started dating soon after, even getting engaged for six months before the relationship ended.Although he appeared to have a squeaky clean image, in 2013 Leandro was accused of assault after a disagreement at a party in London hinting that Katie's ex was more of a bad boy than anyone initially thought.
10 of 11Amy Childs and Bradley Wright
Amy is expecting her first child with boyfriend, Bradley Wright. He already has a daughter from a previous relationship, but Amy has been with him for two years now.Bradley has previously spent time in prison serving sentences for burglary, handling stolen goods and driving offences.
11 of 11Cara Kilby and Daniel Harris
Cara Kilby only had a brief stint on TOWIE, but she was a firm favourite with viewers.Her boyfriend, Daniel, was sentenced to two years in prison after being accussed of leading a gang that sold drugs across London. He is due for release in the next few weeks.