A nine-strong jury has unanimously convicted a 48-year-old estate agent of the brutal murder of 80-year-old Monica Warren after shooting and stabbing the victim at her Costa Blanca home.

State prosecutors said before her trial started on Monday at a court in Elche, south of Alicante, that they wanted her jailed for 28 years for the crimes of murder and arson.

However, the prison demand was lowered to just over 15 years for the self-confessed killer, identified locally only as Yolanda G.R., following her confession on the first day of her trial.

As a result, the trial ended on Wednesday, five days earlier than it had been expected to run. 

Her defence lawyer Joquin de Lacy argued she should benefit from mitigating factors and receive a 12-and-a-half year prison term. 

The trial judge reserved sentencing and is expected to announce his decision in the coming days in a written ruling.

Mrs Warren was stabbed repeatedly and shot three times on the afternoon of May 4, 2022 at her home in Elche. 

Yolanda was arrested and charged along with her teenage son, who died aged 18 in June, a day before his murder trial was scheduled to get underway at a youth court in Alicante after losing control of his convertible Mercedes on the AP-7 motorway near Campoamor, just south of the resort of Torrevieja. He was on bail at the time following an initial remand in a youth detention facility.

The surviving defendant claimed she did not know Mrs Warren had suffered a “psychotic episode” when she killed her as she drove around looking for villas to sell to a client after her victim let her into her home during heavy rain.

State prosecutors alleged Mrs Warren’s killing was a planned assassination and questioned the defendant’s decision to cite mental health issues after failing to cooperate with investigators for two years before the case got to court this week. 

Reports at the time said the British OAP could have been targeted over a real estate dispute, but no proven motive has ever been established. 

The arson charge related to the actions of the self-confessed killer after the murder, when she poured petrol over the car she had used to drive to the dead woman’s house and set it alight in a street in Alicante, damaging a number of other cars. Prosecutors alleged she had been trying to dispose of evidence.

Mrs Warren, who was born in Germany but became a naturalised British citizen through marriage, moved to Spain with UK-born husband John more than 20 years before she was killed. A friend revealed she had worked as a model in London. Mr Warren died of cancer several years before the murder and she lived alone. 

A plumber the Brit had called to her home to carry out an urgent repair raised the alarm after coming across a pool of blood. He told a 999 operator he was concerned because he had seen two people wearing hoodies leaving the OAP’s home and driving off in a black Peugeot who told him the Brit was ill and urged him to return the following day. 

Spanish police said in a statement after the fatal stabbing and shooting that neither suspects had a criminal record, the weapon used had been found and that her body had been moved from the place she was killed to the spot where she was found – under a bed. 

On the first day of the trial on Monday, the defendant said she had “lost her head” and shot Mrs Warren after seeing a “white silhouette” when she knocked on her door during torrential rain. 

She claimed she had been driven mad in the months leading up to the shooting by a “grey-haired” person who was following her everywhere, local paper Informacion reported. 

She alleged she had acted alone initially, although she subsequently asked her teenage son who was in her car outside to help her move the victim’s body while in a “state of shock”.