Reports said the architect and designer studied at Central Saint Martins College of Arts and Design in London, now called Central Saint Martins.
A restaurant worker in a village near to where the horrific discoveries were made told Jornal de Noticias: “Sometimes they came in with the little boy and other times it was just him.
“He wasn’t a person who spoke a lot. Good morning and good afternoon and that was it.”
Initial reports in Portugal indicate police believe Weisshaar and Tasso had been dead for around two days, although post mortems due to be performed later today were expected to pinpoint the exact time of death.
Portugal’s Judicial Police are leading the investigation.
A spokeswoman said: “We have no comment to make at this stage.”
The force would not officially name the suspect.
Weisshaar was described by magazine Forum as “the leading edge of a new generation of digital designers.”
Calls to his offices in Munich and Stockholm went unanswered early this morning.
Globe-trotting Weisshaar and Ms Arnold spent time together in New York, Germany and Portugal together before separating.
Ms Arnold was heavily involved in the world of fashion, having co-founded Ponystep magazine before going on to work as fashion director at magazines including Garage and Elle.
As a stylist she was said to have counted Paloma Faith among her clients, having worked with her since at least 2018.
The singer credited Ms Arnold with creating her look for the British Vogue fashion awards ceremony in February last year, and during Comic-Con in 2019.
Other famous friends are believed to include model Lady Eliza Cummings and designer Katie Jan Hillier.
The Foreign, Commonwealth and Development Office said: “We are supporting the family of a British-German dual national child who has sadly died in Portugal.
“Our consular staff have been in regular contact with the child’s family and local authorities since they were first reported to be missing, and we will continue to support them at this very difficult time.”
