Brian Walshe, center, listens during his arraignment Jan. 18 at Quincy District Court, in Quincy, Mass., on a charge of murdering his wife Ana Walshe. Craig F. Walker/The Boston Globe via AP

BOSTON — Prosecutors in Massachusetts are basing their murder case against a man whose wife is presumed dead but whose body has not been found in large part on a series of gruesome internet searches he made around the time of her disappearance.

Scouring data on personal electronic devices is a common strategy in criminal cases, but experts warn that incriminating searches are not enough alone to build a solid case.

“It would be very challenging to try and base a criminal investigation on just what somebody searched for on the internet,” said Jennifer Lynch, the surveillance litigation director of the Electronic Frontier Foundation, a San Francisco-based nonprofit that defends digital civil liberties.

Brian Walshe used Google to look up ways to dismember and dispose of a body, including “how long before a body starts to smell,” “hacksaw best tool to dismember,” and “10 ways to dispose of a dead body if you really need to,” a prosecutor said when Walshe was arraigned Jan. 18 in connection with the presumed death of Ana Walshe.

Not guilty pleas were entered on Brian Walshe’s behalf.

Ana Walshe, a mother of three, was reportedly last seen leaving the family’s home in Cohasset, south of Boston, in the early morning hours of Jan. 1. She was on her way to the airport for a flight to Washington, where she worked for a real estate company, authorities said. She was reported missing by her employer Jan. 4.

In the Walshe case, the defense will likely bring in its own expert to attack the reliability of the search evidence at trial, which could be years away, said Rachel Fiset, a Los Angeles-based defense attorney.

But the whole of the evidence may be too much to overcome.

“I am having a hard time, other than the fact that there is no body, seeing how Brian Walshe will defend this case,” unless he claims self-defense or insanity, Fiset said. “These searches are really bad, really damning.”

Lynch warned about intrusive searches of what is essentially free speech. Just because someone searches for something potentially illegal online, it is not evidence that they intend to commit a crime, she said.

“We all need to worry about the police having access to our search queries because they reveal so much private information about us,” Lynch said. “So many of our search queries are just idle curiosity.”

Google did not respond to an emailed request for comment. The tech giant publishes regular transparency reports in which it discloses the number of requests made by governments for user information and the number of accounts subject to those requests.

For the six-month period from July to December 2021, the most recent period for which the information is available, Google received nearly 47,000 requests for information in the U.S., and in 84% of those, some data was produced.

“Government agencies from around the world ask Google to disclose user information,” the company said on its website. “We carefully review each request to make sure it satisfies applicable laws. If a request asks for too much information, we try to narrow it, and in some cases we object to producing any information at all.”

There is legal precedent in Massachusetts of securing a murder conviction even when the victim’s remains are never found, and the internet searches could help overcome the lack of a body, Northeastern University School of Law professor Daniel Medwed said.

A Quincy man was convicted in 2002 of killing his wife, whose body was never found after she was last seen leaving her construction job Sept. 27, 1998.

“It’s an obstacle, but it’s not insurmountable” Medwed said. “In any no-body case, there is going to be doubt. So all of the circumstantial evidence has to be air tight.”

In Brian Walshe’s case, there is evidence in his search history of marital discord – he also looked up divorce terms. Medwed said prosecutors have additional evidence of Brian Walshe’s trips to home improvement stores for cleaning supplies the day after Ana Walshe was last seen, as well as blood and DNA evidence that was found on some of Ana Walshe’s personal belongings recovered from a trash facility.

“You add all that together and you create narrative,” Medwed said.

Walshe’s attorney has not commented on the specifics of the evidence but has said that her client has cooperated with investigators.

“I am not going to comment on the evidence, first because I am going to try this case in the court and not in the media,” attorney Tracy Miner said in a statement on the day of Walshe’s arraignment.