Stockholm  - The trial of a German woman charged with beating to death two toddlers in Sweden in March drew to a close Tuesday with questioning of a forensics expert.

The accused, a 32-year-old student, has denied she attacked the children and their mother in Arboga, central Sweden on March 17.

She has told the court that she visited the small town of Arboga at the time of the murders to visit archaeological sites.

Legal experts said the outcome of the trial remains open, noting that there was no DNA evidence linking the accused to the crime scene.

The prosecution has tried to build its case on witness accounts, and during the trial more than 50 witnesses were summoned.

On Tuesday, a forensics expert said DNA samples were spoiled since there were some 18 people including the victims at the crime scene.

Prosecutor Frieda Gummesson has described the attack as a crime of jealousy, with the German woman having refused to accept that her ex- boyfriend had begun a new relationship with the mother of the two children.

The woman was extradited to Sweden at the end of April and held in Vasteras, some 100 kilometres west of Stockholm where proceedings were held Tuesday after earlier being held at a different location.

The defence has questioned the ability of the 23-year-old mother, who sustained injuries in the attack, to accurately remember details of the attack in which her children - aged one and three - were repeatedly beaten to death with a heavy object.

The mother has identified the German woman as the attacker but one of Sweden's leading experts on memory, Professor Sven-Ake Christiansson, earlier testified that her memory was likely impaired.

Police have not found the murder weapon. Gummesson, in her opening statement, said that the accused's former landlady in a Stockholm suburb had in January discovered that a hammer was missing.

The German woman has said she may have borrowed the hammer to repair a bicycle but was also heard by witnesses as saying she disposed of a hammer before flying back to Germany after the murders.

Closing arguments are due August 25. (dpa)