Authorities have released the pair but banned them from leaving the country after warning them they could face up to ten years in prison if found guilty of a charge of aggravated abandonment of a child.
The unnamed Chinese couple, thought to be in their late thirties, had been given permission to settle in Portugal under its Golden Visa scheme because they had invested more than €500,000 in property.
The luxury condominium where the tragedy occurred is in Parque Das Nacoes, one of Lisbon”s most exclusive addresses.
Their daughter, who they left alone to go to Lisbon Casino 600 metres from where they live, is thought to have plunged to her death after waking up and climbing over metal railings on the verandah.
Her parents raised the alarm just after 3am on Friday as they returned from their night out.
They were taken into custody after their daughter”s body was found on a patio next to the Vasco da Gama shopping centre below their apartment.
Local reports said the pair, who come from the Xangai region of southern China, used the flat as a holiday home and had been in Portugal around a week.
Duplex apartments in the condominium where they were staying fetch upwards of #700,000 (€900,000).
The dead girl”s parents have been described as entrepreneurs although details about their exact professions have not been made public.
A spokesman for prosecutors in Lisbon confirmed: “A criminal inquiry is underway to clarify the circumstances in which a five-year-old girl died following a fall from the 21st floor of a building in Parque das Nacoes in Lisbon.”
A judicial source said the bail conditions, which include the ban on leaving Portugal and an order to sign on at a court every week, would remain in place for at least three months.
Stunning Brazilian model Jeniffer Viturino, 17, fell to her death from a 15th floor apartment in the same block in 2011.
Her family claimed at the time she may have been pushed to her death but prosecutors shelved their investigation after failing to find any evidence of a crime.
The Golden Visa Programme launched by the Portuguese authorities is a fast track for foreign investors from non-EU countries to obtain a fully valid residency permit in the country.
The conditions for those wishing to qualify including buying property above half a million euros, creating a minimum of 10 jobs of transferring funds above €1million
Some have dubbed the visa the EU residency permit because it allows grantees access to the Schengen zone.
The scheme, introduced in 2012, was suspended briefly last July following a corruption scandal.