New York, Oct 19 (IANS): The backyard photo of Lee Harvey Oswald - who assassinated US president John F. Kennedy - holding the same type of rifle used in the killing is authentic, a new Dartmouth College study says.

The findings refute continued claims that the photo was faked because Oswald's pose was physically implausible.

The study used a new digital image forensics technique and a 3D model of Oswald.

"Our detailed analysis of Oswald's pose, the lighting and shadows and the rifle in his hands refutes the argument of photo tampering," said senior author professor Hany Farid.

Oswald was killed before his trial. So he never gave a full account of the November 1963 assassination, which fuelled theories that he was part of a conspiracy.

The theories point to purported inconsistencies in the events of the fateful day, and in the evidence collected against Oswald.

One example was the photograph of Oswald in his backyard holstering a pistol and holding a rifle in one hand and Marxist newspapers in the other.

The photo was particularly damning because it showed Oswald holding the same type of rifle that was used to assassinate Kennedy.

At the time of his arrest, Oswald had claimed the photo was fake.

In addition, it has long been argued that the lighting and shadows in the photo were inconsistent, that Oswald's facial features were inconsistent with other photos of him, and that the size of the rifle was inconsistent with the known length of that type of rifle.

Another objection was that Oswald's pose was physically implausible. It looked as if he was standing off balance.

Earlier studies have refuted the claim that the lighting and shadows were inconsistent, but these studies did not address claims that Oswald's pose was physically implausible.

In the new study, the researchers built a physiologically plausible 3D model of Oswald and posed this model to match his appearance in the backyard photo.

By adding the appropriate mass to each part of the 3D model, they were able to perform a balance analysis on the model.

This analysis revealed that although Oswald appears off-balance, his pose is stable.

The analysis also revealed that the lighting and shadows were physically plausible and the length of the rifle was consistent with the length of the rifle used to kill the president.

"Our analysis refutes purported evidence of manipulation in the Oswald photo," Farid said.

The findings appeared in the Journal of Digital Forensics, Security and Law.