On the respected television news magazine 60 Minutes, to be broadcast tonight, two California doctors say they believe the child, who died in February 1997 from brain trauma, was strangled up to 48 hours before being rushed to hospital from the home of Sunil and Deborah Eappen, where she worked.
Ms Woodward, who is interviewed on the programme, was finally allowed to leave the US last summer, but with a manslaughter conviction. These new claims that death was brought on by strangulation leave open the possibility another person could have been responsible.
"If we view this as serious evidence, we will seek to talk to the experts and see what they've got," said Harvey Silverglate, Ms Woodward's lawyer in Boston. "It's never too late to get a conviction overturned, but we're not at that point yet."
Martha Coakley, who led the prosecution, was scornful, however. "This child clearly died from blunt trauma to the head," she said. "There's no doubt... that we had the right verdict."
The two doctors, both from Children's Hospital in Los Angeles, apparently base their findings on evidence of bruising around Matthew's neck. Strangulation, they argue, would have led within about 48 hours to a traumatic swelling of the brain.
Laywers for the Eappens called the claim "preposterous". They insist the bruising was caused by efforts to resuscitate the child after admission to hospital.