You're in luck, our housemate has that game.
So they're a bit more slender and proportioned more like true humans than wargames miniatures, so smaller heads, hands, feet than is typical for a wargaming mini. They're also a bit on the taller side - I compared some to Copplestone minis and they were 1-3 mm higher on average.
I think they would work together alright as the heads aren't THAT much smaller and the scale isn't massively different. I've certainly used larger miniatures than these (the Cluedo minis) and they still work with the Copplestone figures I'm using. Especially for characters like the young ladies, where the slender proportions will work.
However, if you're using older minis closer to true 28mm, I'm not sure these investigators would work as well as the height difference will be more substantial.