Olubunmi Diya lost daughter Comfort Diya, nine, son Praise-Emmanuel Diya, 16, and husband Gabriel Diya, 52, in the incident on Christmas Eve at the Club La Costa World in Fuengirola.
Mrs Diya previously said in a statement all three could swim and claimed "something was wrong" with the Spanish hotel pool.
Hotel operator CLC World Resorts and Hotels has said Mrs Diya's claims are "directly at odds with the findings of the police report".
In a statement it stressed police findings made it "clear that their exhaustive investigations have confirmed the pool was working normally and there was no malfunction of any kind".
An English translation of a Guardia Civil statement, released by the hotel operator, stated that tests had found "no irregularity" in the pool's system.
It said investigations indicated the accident was "caused by the lack of expertise of the victims when swimming".
But Mr Toro was quoted by the BBC as saying: "It's very rare for three people to die in the centre of a swimming pool - especially in the case of a tall, hefty man.
"Something must have happened apart from a simple error or simple accident."
He said the family is "not satisfied with the interpretation of it being a simple accident".
"Clearly the death of three people at the same time in a pool makes it evident that something very strange happened. It's an event that must be studied," he said.
"We do not discard the option of opening a parallel investigation through different engineers... to figure out what happened".
According to the BBC, Mr Toro said the family hoped to be given the detailed police report on the deaths next week.
The "utterly heartbroken" Mrs Diya has said her loved ones, who were reportedly on holiday with another unharmed daughter, were not left unattended and were somehow "dragged into the middle" of the pool.
They followed the instructions displayed by the poolside at all times, she said.
Mr Diya's Facebook account lists him as a pastor at Open Heavens London, a Christian religious group with origins in Nigeria, based in Charlton, south-east London.
It is part of the Redeemed Christian Church of God and worships at the St Richard's Church Centre in Charlton.
Around five well-wishers arrived at the centre in the hope of paying their respects to the Diya family on Sunday morning, but left after it appeared no service would be taking place.
Outside the nearby family home, where flowers and cards were left by the front door, friends and family gave tributes.
Mrs Diya's childhood friend from Nigeria, Elizabeth Moses-Mullard, 47, from the Heathrow area, said they had exchanged messages since the incident.
"It's a really, really, very sad experience, it's a traumatic experience," she said.
"I can only keep my thoughts and prayers with her."
She said she felt "upset and angry" over the investigation into the incident so far, adding: "I want an independent investigation conducted and justice for my friend and her family."
Mrs Diya's tearful cousin, Doyin Akintokun, said she had only heard of the incident on Saturday.
"I just put myself in [her] shoes, how would I cope?" she said.
She added: "Thinking about it, how can this happen?"
Ms Akintokun called for a "good investigation" to "get to the route" of what happened in the incident.
"The damage is done, nothing can bring this family back," she said.