Dr Fia Johansson has been granted power of attorney over the woman who claims to be Madeleine McCann.
The celebrity psychic has been helping Julia Wendell who believes she is the missing girl who disappeared at the age of three in 2007 while on a family holiday in Portugal.
Taking to her Instagram Story to announce the news, Dr Johansson wrote: "Today I got Julia’s power of attorney. I legally and officially can decide Julia’s living and her health and welfare.
"Good news for Julia’s fans and followers. Bad news for people who can’t use her anymore."
The private investigator had previously claimed that people have been trying to scam Julia, who also goes by the name of Julia Faustyna or Julia Wandelt.
She said police are investigating the online trolls.
A power of attorney is a written authorisation to represent or act on another person's behalf in private affairs, business, or legal matters.
Julia is currently waiting for the DNA results which will confirm or deny her suspicions that she is Madeleine.
Julia recently appeared on US talk show Dr Phil to discuss her suspicions.
During the interview, Julia said she has just one memory from her early childhood which is of being by a beach and the ocean.
Addressing the audience, Dr Phil said: "What she remembers is eerily similar to the place where Madeleine McCann was last seen alive."
Discussing her only early memory, Julia said: "I have some single memories since eight, nine years old.
"And before eight, I have only this one memory with beach and water, like sea or ocean, and there were turtles and children trying to catch the turtles and take them in their hands.
"And I remembered light-coloured buildings, like white or very light colours, sunlight on this building."
Her family remain adamant that Julia is their biological child.
Julia was read out a statement from her parents who said they have neem left "devastated at this current situation".
However, the 21-year-old remained adamant that she is Madeleine and said she doesn't want contact with her family.
She stated: "I believe I am Madeleine McCann. If she is my mother, I don’t want to have contact with her that’s all, but I believe she isn’t my mother."
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