The partner of the British mother accused of killing her two small children in Spain has appeared in court on Wednesday on charges of child rape.
Martin Anthony Smith, 45, from North Shields, was seized in Barcelona on Friday.
One of Britain's most wanted, he had been on the run for nearly two years.
His wife, Lianne Smith, is being held in Spain on Wednesday, accused of killing their two children - Rebecca, aged five, and Daniel, aged eleven months.
The children's bodies were found in a hotel room in Lloret de Mar near Barcelona on Tuesday afternoon.
Mrs Smith has allegedly confessed to the killing in a note.
Unconfirmed reports claimed she suffocated the children with a plastic bag amid fears that authorities would take them away from her.
She has not yet been charged with any offence. She is due to appear in a Spanish court on Wednesday or Thursday.
Smith appeared at Carlisle Magistrates' Court on Wednesday morning to face 13 charges of sexual offences and for failing to answer police bail.
A Cumbria police spokesman said: "During the court hearing it was disclosed that Spanish police have informed Cumbria Constabulary that Martin Smith's wife, 43-year-old Lianne Smith, has been arrested on suspicion of the murder of his two children Rebecca, five, and Daniel, 11 months, in Spain.
"Lianne and Rebecca had been missing from the Staffordshire area since December 2007."
Smith, one of Britain's most wanted, was arrested in Barcelona last week in connection with a rape of a child under 16, gross indecency with a girl under 16, indecent assault of a girl under 16, and attempted rape of a girl under 16.
The alleged attacks took place between April 30, 1995 and April 29, 2005.
On Wednesday he was remanded in custody until his next court appearance.
Earlier it was reported that Smith had jumped bail and fled Britain in 2008 with Lianne and Rebecca.
It has not been confirmed if all three were in Spain together.
The respected El Pais newspaper, quoting local police sources, said Mrs Smith had left her confession in the form of a note.
She asked staff at the beachfront Hotel Miramar in Lloret de Mar on the Costa Brava to phone for police and an ambulance at around 3pm on Tuesday.
When hotel staff asked why, she reportedly would only reply: "You will see."
Police were called and made the horrific discovery in Room 101 of the four-star hotel.
Local police found the bodies of Rebecca and Daniel lying on the beds of the triple room, carefully covered with a blanket, local newspaper Diari de Girona said.
There were no signs of violence.
A worker at the hotel said the two officers brought the mother down from the room and sat her in reception.
After being questioned by police, the woman returned to the hotel room - in handcuffs - to help carry out a reconstruction for investigators.
She was taken away from the Hotel Miramar shortly after 6.30pm.
She was reportedly heckled by a crowd of several dozen in front of the hotel as she was led away by police.
Sources said police were searching rubbish bins near the hotel for sleeping pills or tablets that may have been used to overdose the youngsters.
On Wednesday morning police would not confirm reports that the two were suffocated with a plastic bag.
Mrs Smith was also said to have been seen in the resort in the company of a man, who officers are trying to find in case he can shed any light on the deaths, Diari de Girona reported. He is not a suspect.
British holidaymakers laid flowers at the front of the hotel last night, one saying: "RIP little ones. God has gained two angels."
Officers from the Catalan regional police force took over the investigation from the municipal police in Lloret de Mar.
The judge investigating the deaths has ordered police inquiries be carried out in total secrecy.
A spokesman said: "Around 3.53pm officers received a call from the local police in Lloret de Mar, asking them to go to a hotel where the lifeless bodies of two youngsters had been found.
"When the officers arrived they established that there were two dead minors inside one of the hotel bedrooms.
"Officers from Girona are investigating the death of the two children and arrested the mother of the two minors for her suspected connection with those events.'
A source in the Area Territorial Investigation branch of the police told the Daily Mail: "All we can confirm at present is that the bodies of two children were found in a room at the Hotel Miramar.
"The boy is aged one and the little girl is aged about five. We are still making inquiries.
"However, we can confirm that the mother of the two children has been detained by our officers and is being questioned.
"At this early stage we cannot say exactly how the children died. We have forensic officers at the scene and more details will emerge in the coming days."
A French family staying in the room above, on the second floor, said they saw the two children playing on the balcony on Monday.
They said the mother ordered them to go back inside. But they heard nothing out of the ordinary on the afternoon the children died.
The Frenchman, staying in the resort with his wife and a baby, said: "We saw her on Tuesday morning. She was pale and had bags under her eyes. She looked bad.
"The previous day we'd been struck by the fact her daughter spent a lot of time playing alone on the balcony, which is not a place to leave such a small girl."
The unnamed holidaymaker added: "We are horrified that this awful crime has been committed in the room below us."
On Tuesday night a judge from a court in the nearby town of Blanes, who is set to oversee the investigation, was at the Hotel Miramar and speaking to staff.
The bodies of the children have been transferred to the Institute of Legal Medicine in Girona and will be examined by a pathologist on Wednesday.
Mrs Smith checked into the hotel with the children on Saturday.
She was not part of a package deal with a tour operator and had made the reservation by phone before paying in advance for four nights' accommodation.
The family had been expected to check out of the hotel on Wednesday.
Sources within the Hotel Miramar said the woman arrived by car with the children.
A hotel spokesman refused to discuss the tragedy.
A Foreign Office spokesman said only: "We have seen and heard reports and we are investigating."
Lloret de Mar is popular with both younger holidaymakers and British families and the hotel strip is close to the beach, a green area and water park. - Daily Mail