A Brazilian investment fund that owned 40% of Neymar`s sports rights argues it was deprived of its full share.
In previous interviews, Neymar, 24, has denied any wrongdoing.
Barcelona said it paid €57m (£43m) for Neymar in 2013, with the player`s parents, Neymar da Silva Santos and Nadine Goncalves da Silva Santos, receiving €40m and his former club, Santos, €17m.
But investigators say the fee was closer to €83m and Barcelona concealed part of the deal. The club also denies any wrongdoing.
Success on the pitch
The Brazilian third-party investment fund, DIS, alleges it was financially harmed by the transfer when it received €6.8m of Santos`s €17m fee and argues it was deprived of its full share.
Neymar and his parents, along with Barcelona`s ex-President Sandro Rosell and President Josep Maria Bartomeu, had all given statements at an earlier court hearing in February.
Speaking to O Globo TV in Brazil in February, Neymar said: "Before saying nonsense - that we hid this, or hid that - they should prove it.
"My father is doing everything to ensure that I can just focus on playing football. He handles the books. But in the moment when you see someone you love suffering, it starts to hurt."
Neymar and his father also face accusations in a separate case of defrauding the Spanish tax office, while the player faces a tax evasion investigation in Brazil. He denies wrongdoing.
Neymar`s move to Barcelona FC has been a big success on the pitch. The striker became part of a goal-scoring trio with Lionel Messi and Luis Suarez.
In 2015, Neymar helped the club win five trophies and came third in the Fifa Ballon d`Or competition. He also scored in the Uefa Champions League final against Juventus.
He won the Spanish league and cup double with Barcelona in 2016.
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