Madeleine McCann's parents plan to stay in Portugal to prove their innocence after being named official suspects in the case, friends have told the BBC.
Gerry McCann was questioned for eight hours by Portuguese police
Jon Corner said Gerry and Kate McCann, both 39, were determined the search for their daughter would not be "derailed".
The four-year-old disappeared from the family's holiday apartment in Praia da Luz in Portugal's Algarve on 3 May.
Earlier, a family spokesman said police believed Mrs McCann, of Rothley, Leics, had killed Madeleine accidentally.
No bail conditions, travel restrictions or charges have been imposed on the couple, who had been questioned separately for more than 24 hours.
Mr McCann was officially given "arguido" status 12 hours after his wife.
The move allows the authorities to put certain questions to Mr and Mrs McCann, and also gives them the right to remain silent.
The couple have opted to stay in Portugal despite wanting to return home with their two-year-old twins Sean and Amelie.
Philomena McCann said her brother Mr McCann "doesn't want it to look as if they are running away".
Mr Corner said: "I spoke to Gerry in the early hours this morning and he wasn't surprised that he was named as an official suspect.
"The process of questioning I think is designed to be intimidatory, but Gerry is frustrated by the line of questioning and where the inquiry is going.
"But he's also fighting and I think he's determined that the search for Madeleine is not going to be derailed by this."
Mr Corner said the developments pointed to the "mindset of the Portuguese police".
Officially a suspect
Bestowed by police or requested by individual
Right to remain silent
Right to a lawyer
Must report to police every five days
"Clearly, they're not investigating or doing the detective work to find Madeleine," he said.
"They're actually looking for a very quick, clean closure on the case, and that means turning their focus into the family."
The BBC understands that the police put it to Mrs McCann that she was somehow responsible for the accidental death of Madeleine inside the apartment.
They went on to say that with the help of her husband she then hid the body temporarily and then moved it later using the couple's hire car.
The McCanns vehemently deny such claims.
Mrs McCann's uncle Brian Kennedy said: "The notion that even accidentally they killed their daughter, hid her body, then put her body in a car hired 25 days later while the glare of the international publicity is on them, and when they are always with friends and family, is fatuous beyond words.
"I just find the notion repulsive."
Mr Corner had previously said Mrs McCann told him officers had tried to "cut her a deal" under which she would serve only two years in jail if she confessed.
The media have set up camp outside the McCanns' rented villa
But Portugal-based British journalist Paul Luckman told the BBC that under Portuguese law there is a set sentence for each crime which not even a judge can change.
He said it would not be possible for the police to make such a deal.
Local lawyer Oliveira Trindade said: "Legally, if the prosecutor has enough evidence they have to charge the arguidos within the next 10 days.
"If they don't have enough evidence the investigation will continue."
TV crews and photographers, who had been camped outside the police station in Portimao, have moved on to the McCanns' rented house in Praia da Luz.
Mr and Mrs McCann called off plans to attend a service at the village church of Nossa Senhora da Luz on Saturday night because of the amount of media interest.