Which was stopping the boat and shutting down the engine so he could push the dog crate, the boat fender, and the body overboard. I try to envision it and can’t imagine hoisting a crate containing more than a hundred and fifty pounds of cat litter, dropping it and a body over a high side rail. A dive platform, a boat with an open transom, I consider. The cut-down transom of lobster boats around here that make it easier to launch pots and buoys, boats that are ubiquitous at all hours and in all types of weather, attracting no attention, and I try to reconstruct it.

The open transom of an old wooden boat that’s been repainted, and the crate, the fender, the body pushed into the water at the same moment a gigantic leatherback became entangled with fishing tackle, with an old bamboo pole, is there. I see the strike, the encounter, I almost can. The turtle surfacing for air, dragging the fishing gear wound around him, and running into the bottom of a boat, perhaps glancing off its prop, and now he’s dangerously trussed up in yellow nylon buoy line, weighted down, slowing down, pulling his burden until it almost pulls him under.

It’s quite likely the killer wasn’t aware of the leatherback, knew nothing of what occurred. For one thing, I suspect it was dark, and I imagine the boat near Logan, where the e-mail was sent from Emma Shubert’s iPhone on Sunday at six-twenty-nine p.m., and then this person waited, possibly for hours, until he was sure no one would see him.

“What makes you say a number of years ago?” I ask Ernie. “You’re able to date when the hull originally was painted black?”

“Traces of TBT,” he says.

The paint contains tributyltin oxide, he explains, an antifouling biocide that has decimated marine life—shellfish, in particular—killing them off, causing them to mutate. TBT is one of the most toxic chemicals ever deliberately released into the world’s water and has been illegal in high-traffic areas such as harbors and bays since the late 1980s. But the ban unfortunately doesn’t include oil tankers and military vessels.

“So unless the boat in question is military or a tanker, and I seriously doubt it, then the boat you’re looking for could be at least twenty years old,” he adds, as Benton looks for parking on the street near Machado’s Crown Vic.

Howard Roth has no driveway, his small frame house overtaken by trees and shrubs behind an abandoned factory on Bigelow Street in an area that’s a mixture of historic homes and Harvard apartments and affordable housing. While I can’t see it from where we are, I know that Fayth House is but a few blocks west on Lee Street, an easy walk from here. I continue to wonder if Peggy Stanton might have volunteered there.