I live about four miles from the last radar position but hadn't heard of the accident. Below is a local report, which states that the crash occurred in US waters, but Picture 2 in the NTSB report indicates that the ditching might have been on the Canadian side of the Strait of Juan de Fuca.
https://vancouverisland.ctvnews.ca/s...oria-1.5283658
Since no wreckage has been found and given that it was a US "Domestic" flight, I imagine the TSB were more than happy for the NTSB to take responsibility for the investigation.