The defense attorney, Julia Gatto, urged U.S. District Judge Paul Gardephe to exclude the cellphone data being used to place Officer Gilberto Valle near the workplace of one woman and near the home of another. Prosecutors have said both women were the officer's targets. Jury selection in the case begins Friday.
The 28-year-old was charged last fall with using a law enforcement database to make plans to kidnap, rape, kill and eat women. Lawyers have said he was merely fantasizing and intended no violence. A New Jersey man charged in the case last month will be tried separately.
Gatto said prosecutors had boasted that they could use cellphone records to show Valle was on the same Manhattan block as one of the women and had done surveillance on both of them after writing to a co-defendant about how the women would be eventually harmed.
Yet, she said, cellphone tracking is not as accurate as the government had claimed and records would at best show he was within a half mile of the locations and at worst within 26 miles.
Assistant U.S. Attorney Hadassa Waxman conceded that an FBI agent who will testify about cellphone data could only assure jurors that the information
She said other evidence would support the surveillance claims, including testimony by Valle's estranged wife that she hadn't seen one of the intended victims in more than a year even though Valle told authorities after his arrest that he dropped his wife off there last March and that might explain his phone's proximity to the woman's home.
Gardephe said he was "concerned about what seems to be a lack of clarity about what the cell-side data shows."
He said he might require a phone company employee to testify about the accuracy of efforts to trace where the cellphone signal originates.
"It's an important issue at trial whether there's evidence that the defendant conducted surveillance," Gardephe said.
He noted that it was late in the game for prosecutors to leave such an important area of evidence undefined since opening statements are scheduled to start in late February.
"I've alerted the government and I'm very concerned," Gardephe added.