"When I do a crime scene analysis it is a theory based on evidence to then be given to police and used to look for more proof and evidence suitable for prosecution," she said.
"When I analysed [Madeleine's] case, it led me to believe evidence does not support an abduction.
"An abduction was extremely unlikely based on the amount of time, evidence at the scene, and every other shred of evidence there has ever been."
Brown said Madeleine most likely died in an accident that was "covered up".
"The evidence supports the theory of an accident occurring through neglect and possible medication," she said.
"It's my belief the body was moved to a desolate location and will never be found."
Brown's comments come after British police investigating the disappearance of Madeleine McCann nearly 10 years ago were last week granted £85,000 ($149,000) to extend the search for a further six months.
The British Home Office has granted officers the funds to continue the probe until September.
Police want to speak to a person who was near where Madeleine went missing, the Sunday Express reported.
So far, £11.1 million has been spent looking for Madeleine.
"There are other children missing in the UK who aren't getting this attention that the money should have been spent on," Brown said.
Madeleine disappeared from the family's holiday apartment in Praia da Luz in Portugal as her parents Kate and Gerry McCann dined with friends at a nearby restaurant in May 2007. If alive, Madeleine would now be 13 years old.
Brown said Scotland Yard investigators made a mistake by ruling out suspects early on.
"You only eliminate someone as a suspect if they have an alibi and could absolutely not have committed the crime," she said.
"It shouldn't be based on theories."
Brown said the biggest mistake investigators made was examining and reviewing the case working to the theory that Madeleine had been abducted.
"They came in with a purpose and stated there was an abductor," she said.
"Their focus was on finding a kidnapper."
Brown said there was "no evidence of an abduction" but that didn't mean it hadn't happened.
"On the other hand it doesn't mean it did," she said.
"But because there's no evidence of an abduction one has to look at other possibilities as well."
Brown said it was "extremely unlikely" anyone from a child sex ring would have abducted Madeleine. She said children could be illegally bought in some poor areas or "easily taken from drug addicts and prostitutes".
"Even blonde ones," she said.
'They're not going to steal a British tourist from a holiday resort because they know that will prompt a major investigation into them."
Kate and Gerry McCann have always denied any involvement in her death and vowed to "never give up" hope of finding their daughter.
"As a parent of an abducted child, I can tell you that it is the most painful and agonising experience you could ever imagine," Kate McCann wrote on the couple's "find Madeleine" website.
"My thoughts of the fear, confusion and loss of love and security that my precious daughter has had to endure are unbearable - crippling.
"And yet I am not the victim, Madeleine is.
"No child should ever have to experience something so terrible."
Last month, Kate and Gerry McCann lost their appeal in Portugal's Supreme Court over a controversial book by former detective Goncalo Amaral called The Truth of the Lie.
In it, he claimed Maddie had "died" and her abduction was a "cover-up".
Amaral led the initial investigation into Madeleine's apparent abduction.
The McCanns have lodged a formal complaint against the ruling and are reportedly considering taking their case to the European Court of Human Rights.
The parents are bracing themselves for the heartwrenching 10th anniversary of Madeleine's disappearance in a few weeks.
