CBC reports (http://www.cbc.ca/news/canada/ottawa/frederick-john-hatch-homicide-cellphone-texts-1.3821821) that police "will be sending texts to about 7,500 people on Thursday to ask for information" to individuals that were, according to the cell phone tower logs, within the tower area near the time of the incident.
While we have heard lots of stories about cell phone tower logs being used in policing before (they are even discussed at length in Season 1 of Serial), I think this is the first case where they have been used to actively contact potential witnesses.
A news release by the police states that the texts will ask the recipient to "voluntarily answer a few simple questions to possibly help the Ontario Provincial Police solve this murder". CBC reports that "Investigators will also consider calling the numbers of people who don't respond voluntarily, but they would be required to obtain another court order to do so."
On one hand, this seems like the natural progression from the traditional approach of canvassing local residents by putting up flyers and knocking on doors. Indeed, the investigators use the term "digital canvas" to describe their plan.
On the other hand, I think one can reasonably ask — Are we OK with this approach? For example, presumably, it would be possible to get a better view of who was in the area by checking credit card transaction logs for all stores within the area. License plate readers and speed cameras might also give information about which vehicles were in the area. There are many levels of tracking that could be used simultaneously as a means of generating lists. The question is, do we want this to happen whenever there is a major crime? A minor one? Maybe this is just how things work now, and it really is no different than walking around, knocking on doors. I figured it was worth a discussion at the very least.