Clemens Weisshaar is thought to have shot himself dead after killing his son and setting light to the car he had left the child’s body inside.
The two bodies were found close to together near a village in Portugal.
The mum of the three-year-old boy is reportedly British stylist Phoebe Arnold.
Police have not commented officially on the incident, however the newspaper Jornal de Noticias named Weisshaar and son Tasso.
The paper said Weisshaar had separated with the child’s mother in July, and she had moved to Lisbon with their son.
He had not seen the little boy until the end of October when he went to the Portugese capital and ‘promised’ to return him on November 1 after spending some time with him.
The newspaper said he had reneged on the verbal agreement and she went to authorities to report them missing the same day.
Local reports naming Weisshaar said the 44-year-old German architect and designer had studied at Central Saint Martins College of Arts and Design in London, now called Central Saint Martins.
His website says his designs had been exhibited at institutions including the Museum of Modern Art in New York and the Centre Pompidou in Paris.
He first trained as a metalworker before studying design in London and his business partner is American Reed Kram, who has a background in computer science and maths as well as design.
They founded Kram/Weisshaar in Munich and Stockholm in 2002.
The child’s body was reportedly found near to a remote piece of land the child’s parents had bought to build a house on.
Searches had taken place in the area but nothing had been found before hunters made their grim discovery and alerted authorities.
Initial reports in Portugal point to police reaching the conclusion the German man and his son had been dead for around two days, although an autopsy due to be performed later today is expected to pinpoint the exact time of death.
Weisshaar’s studio has not yet responded to requests for comment.
Clemens Weisshaar has been named locally as the boy’s father (Picture: Solarpix)