Lois Goodman, 70, was arrested in August while she was preparing to officiate at the US Open Tennis Championships and accused of killing her 80-year-old husband, Alan Goodman, at their home in Los Angeles on April 17.
"The DNA on the coffee cup came back solely to the husband and not to Ms. Goodman, which supports our theory that the husband was holding the cup and then he fell on the cup, and that accounts for the shattered pieces of the cup being embedded in the right side of his head," attorney Robert Sheahen said.
The DNA testing results were included in exchanges of materials between defense attorneys and prosecutors as part of the pre-trial discovery process, Sheahen said.
Sandi Gibbons, a spokeswoman for the Los Angeles District Attorney's Office, declined to comment on Sheahen's statements.
"We're not going to try this case outside of court and we're not going to comment on the evidence until it's actually testified to in the court of law," Gibbons said.
The defence discussion of the DNA testing came one month after Goodman's lawyers said she had passed a lie detector test set up by her attorneys in which she denied killing her husband.
Sheahen said the polygraph results had been shared with prosecutors. But under California law, the test cannot be presented in court unless both prosecutors and defense attorneys agree, which Sheahen acknowledged is unlikely.
The next hearing in the case is scheduled for December 7.
Prosecutor John Lewin of the major crimes division has been assigned to the case. Lewin has prosecuted a number of complex, high-profile trials, including one in 2007 where a former Los Angeles County sheriff's deputy was convicted in the 1991 murder of his wife, even though her body was never found.
Police said Goodman called authorities to report finding her husband dead in their home, with no sign of forced entry, and surmised he had fallen down some stairs after suffering a heart attack.
But details of her account aroused suspicions, and investigators found that the coffee cup was broken in a way that roughly matched the injuries on Alan Goodman's head.
Sheahen said Goodman was likely holding the mug and that, at the end of a fall down the stairs, he would have smashed his head against the cup.
Goodman is well known in tennis circles and had worked at the annual US Open in recent years, serving most often as a line judge. A judge has allowed her to remain confined at home while the case proceeds.