When Radnor Township Police Superintendent William Colarulo scrolled through his emails last week, he came across a message that just about made his blood boil.

It was sent nearly 16 hours after investigators had found Meredith Chapman, an assistant vice president at Villanova University, shot to death in the kitchen of her home on Lowrys Lane. Chapman's killer, Jennair Gerardot, was discovered there, too, dead from a self-inflicted gunshot wound.

"In light of the tragic incident that occurred on Lowry's last night," the email began, "I feel compelled to tell you about something I observed on Saturday."

The author of the email, a neighbor who lived not far from Chapman, explained that she noticed a woman standing near her driveway on the afternoon of April 21. "She had a grim, concerned or worried look, and I thought she might have lost a pet," the neighbor wrote, according to Colarulo.

There was another detail, too. The woman was clutching a pair of binoculars. And she was staring intensely in the direction of Chapman's house.

The scene lasted only for a moment. The woman with the binoculars then climbed into a black SUV with a New Jersey license plate and drove away. The neighbor said she didn't think to call police at the time because the activity didn't seem particularly criminal, just strange.

Investigators later found a pair of binoculars — along with bullets, gloves and ear plugs — in a rented Cadillac that Gerardot, 47, drove from her home in Wilmington to Radnor on the day of the crime.

Gerardot shot Chapman after discovering that the 33-year-old had been having an affair with her husband, Mark Gerardot, 49, a former creative director at the University of Delaware. In the months leading up to the murder-suicide, Jennair expressed despair over the gradual deterioration of her marriage in a string of comments she posted on the neighborhood app NextDoor.

Colarulo and Robert Zienkowski, Radnor Township's manager, both sounded frustrated on Monday as they discussed the public's aversion to calling 911 when they spot something unusual. Each recalled lectures they'd delivered at numerous community meetings about the importance of contacting police.

"We tell people all the time," Zienkowski said, "but it falls on deaf ears."

Colarulo said residents often tell him they refrain from calling police because they're afraid to bother them with some trivial matter, or to become entangled in an investigation. But tips can be made anonymously, and even small details have a way of carrying unexpected significance.

Had Chapman's neighbor contacted police last weekend, Colarulo said, his officers would have at least paid Chapman a visit and asked a few basic questions.

"Could the results have changed? We'll never know," he said.

There's a chance that Chapman might have offered up some information about Jennair Gerardot.

"Through our investigation, information was revealed to us that would indicate [Jennair] took certain steps to prevent this woman from having any happiness," Colarulo said. He declined to elaborate.

Mark Gerardot, who ventured to Chapman's house on the night of her murder after becoming concerned when she didn't show up for a planned dinner meeting, has cooperated with investigators. He has not responded to requests for comment.

Chapman's family has declined to comment since her death. Last week, they released a statement through a spokesman that read in part:  "We understand that the circumstances of her death are the focus of news attention today, but we have chosen to refrain from participating in these stories because they do not and cannot capture the essence of her life."

Chapman had been married to former Newark City Councilman Luke Chapman. The couple divorced earlier this month, a split her family described as amicable, and friends have said Chapman was excited to begin a new chapter in her life.

Their divorce decree was mailed on April 25 — two days after she was killed.

Staff writer Erin McCarthy contributed to this article.