As the Spanish Civil Guard continues its investigation into the killing of Singaporean Audrey Fang, a pair of limited edition Nike trainers could prove to be a critical piece of evidence. On April 9, the 39-year-old, who was on a solo trip to Spain, left her belongings in her hotel and was never heard from again. Her body was found a day later with 30 stab wounds near a parking area for lorries in the town of Abanilla. A preliminary autopsy report found that knife wounds and head trauma were the cause of her death, reported Spanish media outlet La Verdad de Murcia. Her suspected killer, Mitchell Ong, was arrested in Alicante on April 16 and appeared in court last Friday. On Tuesday, La Verdad reported that detectives honed in on the €935 (US$1,000) limited edition Nike shoes that were found in Ong’s hotel room when he was arrested in Alicante. Cash in the form of €3,760 and S$1,000 was also found in the room and seized. According to the newspaper, the soles of the shoes match the footprints found at the crime scene. The Spanish Civil Guard has since sent a sample of the soil embedded in the soles for laboratory analysis to determine if it matches the soil found on Fang’s body. They are also looking to compare that sample with the sandstone found in the Abanilla area. The shoes are of particular importance to the police due to their exclusivity – they retail for €935 on luxury clothing website Farfetch, and are European size 48.5. That size corresponds with Ong’s build and 1.88m height. Court documents seen by La Verdad have also detailed other evidence building against Ong. A judge in the Magistrates’ Court of Cieza, which is overseeing this case, noted what the suspect wore on the evening of April 9 when Fang was last seen, and when he returned a few hours later. Closed-circuit television cameras at the hotel where Ong was staying captured the 43-year-old leaving at around 5.45pm while dressed in a hoodie and black pants. He returned to the hotel in the early hours of April 10 at around 2.06am, wearing jeans and a blue jumper. Ong, who got married in 2012 and owned several businesses in Singapore, was due to meet his Ukrainian girlfriend at the same hotel the following day, reported La Verdad. Spanish police have proven that both Fang’s and Ong’s mobile phones were together in Abanilla on the day she died, according to local newspaper Levante El Mercantil Valenciano. It added that she was not sexually assaulted and that the two had known each other for many years. The judge said it is inferred “without a doubt” that both Singaporeans were in the same area and in the same time slot on the day the crime was committed, based on data provided by mobile phone operators in Abanilla. Ong is currently remanded in custody, pending investigations, and he will remain in jail due to the seriousness of the offence. He is also considered to be a flight risk. The judge noted that Ong is a Singaporean with no roots in Spain, and has “sufficient economic capacity” to leave the country. Both the prosecutor’s office and the Spanish lawyer hired by Fang’s family, Manuel Martínez, have demanded that Ong’s remand be extended. The report by Levante El Mercantil Valenciano said there might have been an “economic motive” for the killing, adding that Fang had reportedly transferred money to an unidentified third person. Sources also told La Verdad of an “economic motive”, corroborating Levante El Mercantil Valenciano’s report, while adding that she took part in a type of investment fund. However, it is not ruled out that the murder was committed over a sentimental issue.