Members of the emergency services carry out the body of one of the two murdered children from a hotel in Lloret del Mar on 18th May.
"A statement made by (Smith) in detention confirms one she made earlier confessing to the murder of her two minor children," the judge at the court in Blanes, eastern Spain, said in the ruling.
"There are notes purportedly written by the accused, found at the scene, which are self-incriminating. Ms. Smith acknowledges she ended the lives of her children by suffocating them by placing their heads inside plastic bags."
Police detained Smith on Tuesday, the same day that her husband and the father of at least one of the two children, 45-year-old Martin Smith, was extradited back to Britain from Spain to face charges of sexual offences with minors.
The judge said that Lianne Smith had left her home in Barcelona because she feared she would lose custody of her children following her husband's arrest on May 6, and moved to the Hotel Miramar, "which produced the fatal outcome."
She was ordered held without bail due to the "high risk" she would flee, given that she is a foreign national, "the nature and severity" of the alleged crimes and the fact that she and her husband had fled to Barcelona to escape authorities in Britain.
Lianne Smith faces 15 to 20 years in prison if tried and convicted.
British media has said she checked into the 54-room hotel on Saturday with her two children after arriving by car and paid in advance for four nights.
Spanish media has said she had tried to kill herself and left a suicide note after her alleged crime, before asking a hotel receptionist to call an ambulance.
Autopsies on the two children found no evidence that they had been sexually abused, and confirmed they had died from suffocation.
Lianne Smith had been reported missing in England since December 2007 and police believe she had been living on Spain's Costa Brava.
Martin Smith was arrested in Barcelona after being placed on a list of top suspects wanted in Britain who are believed to be living in Spain, following his failure to answer bail in January 2008.
He was wanted in connection with the rape of a child under 16, gross indecency with a girl under the age of 16, indecent assault of a girl under 16 and attempted rape of a girl under 16.
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"There are notes purportedly written by the accused, found at the scene, which are self-incriminating. Ms. Smith acknowledges she ended the lives of her children by suffocating them by placing their heads inside plastic bags."
Police detained Smith on Tuesday, the same day that her husband and the father of at least one of the two children, 45-year-old Martin Smith, was extradited back to Britain from Spain to face charges of sexual offences with minors.
The judge said that Lianne Smith had left her home in Barcelona because she feared she would lose custody of her children following her husband's arrest on May 6, and moved to the Hotel Miramar, "which produced the fatal outcome."
She was ordered held without bail due to the "high risk" she would flee, given that she is a foreign national, "the nature and severity" of the alleged crimes and the fact that she and her husband had fled to Barcelona to escape authorities in Britain.
Lianne Smith faces 15 to 20 years in prison if tried and convicted.
British media has said she checked into the 54-room hotel on Saturday with her two children after arriving by car and paid in advance for four nights.
Spanish media has said she had tried to kill herself and left a suicide note after her alleged crime, before asking a hotel receptionist to call an ambulance.
Autopsies on the two children found no evidence that they had been sexually abused, and confirmed they had died from suffocation.
Lianne Smith had been reported missing in England since December 2007 and police believe she had been living on Spain's Costa Brava.
Martin Smith was arrested in Barcelona after being placed on a list of top suspects wanted in Britain who are believed to be living in Spain, following his failure to answer bail in January 2008.
He was wanted in connection with the rape of a child under 16, gross indecency with a girl under the age of 16, indecent assault of a girl under 16 and attempted rape of a girl under 16.
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