Russian leader Vladmir Putin has called the shootings in a school in Connecticut "particularly tragic" as the majority of the 28 killed were children.
The Kremlin said in a statement:
Vladimir Putin asked Barack Obama to convey words of support and sympathy to the families and friends of the victims and expressed his empathy with the American people.
More top news
The significant development came after a forensic re-examination of a palm print left on a getaway vehicle.
Carla Lane was once one of the UK's highest paid screenwriters.
Politicians, royalty and the descendants of combatants in the Battle of Jutland commemorated the 8,648 seamen who died in the engagement.