Ironically ran into the controller, I heard on hi level last night, at the grocery store this afternoon. He told me Canadian and American SAR organizations both sent up aircraft...Canadian's reached area first but when they realized signal was on the US side of the border they turned back and US SAR units effected the scene assessment. Also other tidbit, I did not realize that the ILT's carried by ships and fishing boats also transmit on 121.5 .....he says a big frig the first day of fishing and/or lobster season along the Canada / US east coast.
I asked if Canadian/American boundaries were respected in these cases ; he said YES...EXCEPT if it was an "intercept"...then borders don't make any difference. Interesting .....