A Chilean man has been charged with the murder of Japanese astronomer Koichiro Morita in Santiago earlier this week.
Prof Morita, 57, was part of an international team involved in building the Alma radio telescope facility in northern Chile.
He was found collapsed outside his apartment in Santiago last Monday and died hours later in hospital.
Christopher Quijada, 25, is accused of killing him during a street robbery in the early hours of the morning.
Initially it was thought Prof Morita died as a result of an accidental fall, but an autopsy found he was struck on the head with a heavy object.
The authorities say Mr Quijada has confessed to tripping him over as he tried to escape being robbed, causing him to hit his head on the pavement, but denies murder.
The suspect will be held in custody while the investigation continues.
If convicted of robbery and homicide he faces a minimum of 10 years in jail.
Koichiro Morita was a leading figure in creating the Alma Observatory in the Atacama desert in northern Chile.
The Observatory said it was "saddened and deeply shocked" at the news of his death.
"He was one of the proponents of Alma as a global collaboration, bringing together people from all over the world to make what was just a vague concept into a reality," observatory director Thijs de Graauw said.
The giant radio telescope will enable scientists to gaze deeper into space than ever before and may shed light on the formation of our universe more than 13 billion years ago.