Get all PageItems in a layer?

when I ask for all pageItems in a document, like so:

app.activeDocument.pathItems

I get all the pageItems of the current document, regardless of where they are. But when I ask for al the pageItems of a particular layer

app.activeDocument.layers[1].pathItems

I only get the pathItems at the top level of the layer. Any pathItems that are buried in a groupItem aren't returned. Is there a way to see all pageItems in a layer whether they're in a group or not?