“The signature appears consistent with the Sterling trial batch, though we still need original custody documents before we can say who possessed it.”
I read the identifier twice.
“How can you recognize a batch from almost twenty years ago?”
“The reference library is kept for validation, and one retired analyst remembered the unusual pigment.”
“Could somebody make more?”
“A specialist could make something similar, but a match across several properties would be difficult to explain as coincidence.”
Hannah asked whether the particles might have entered my pool through groundwater.
Mara shook her head cautiously.
“The distribution pattern is concentrated at the deck edge.”
“We did not find the corresponding signal in your well sampling point or municipal supply.”
“So somebody carried it there?”
“That is one plausible explanation.”
“Not the only one,” I said.
Mara smiled.
“You’re still a technician.”
She explained that rainwater running across the deck could transport material, which left open the question of where it originated before reaching the concrete.
The most troubling result came from a sample collected from the underside of the silver-blue deposit.
It contained ordinary soil minerals matching the red clay found near the old factory drainage corridor.
That did not prove the clay came from Sterling, but it suggested the particles had traveled with soil rather than arriving in a sealed swimming pool product.
Mara slid a second page toward us.
“There is something else.”
The batch identifier corresponded to a small set of reference containers marked as missing during the original cleanup project.
The incident was recorded but never explained in the public summary.
“Missing when?” Hannah asked.
“The year the plant closed its final storage yard.”
I remembered the empty plastic sleeve in my shed.
“Do you have a picture of those containers?”
Mara turned her laptop around.
The archived photograph showed silver cylinders with flat screw tops.
My pulse quickened.
The object beneath Meredith’s towel had looked exactly like one of them.
Mara leaned back.
“Tell me what you’re thinking without turning it into a conclusion.”
“I think Meredith may have brought an old tracer container to my pool.”
“Why would she do that?”
“I don’t know.”
Hannah touched my elbow.
“And somebody searched Dad’s shed for an old Sterling document.”
Mara’s expression changed.
“You need to tell the detective about both facts.”
“We will.”
She walked us to the door, then stopped beneath the exit sign.
“There’s a name on the original batch authorization,” she said.
