The 27-year-old, from Livingston, died after a fall from the tenth-floor balcony of an apartment in Benidorm after a night out with friends.
Spanish police believe Mrs Maxwell, from Livingston, jumped from the balcony, but family members are adamant that she lost her grip after scaling the barrier.
They have also demanded answers from five English men – all from Nottingham – who were in the apartment at the time in April 2017.
The BBC reports that the investigators, hired by Ms Maxwell’s family, aim to question local people and tourists who holiday there at the same time every year.
The hope is to uncover information to assist the court-led investigation.
In February, Ms Maxwell’s family said they have new hope of establishing what led to her death after forensic experts agreed to review the case.
Mrs Maxwell had flown out to the Spanish resort with a group of friends for a hen party in April 2017.
Her family have said they want “answers” from the men in the apartment, who have denied any responsibility for Mrs Maxwell’s death.
One of the men, Joseph Graham, was arrested on suspicion of homicide but later released without charge.
He issued a statement saying he was innocent of any wrongdoing and described Mrs Maxwell’s death as a “tragic accident”.
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