DETROIT (AP) — U.S. safety regulators are demanding that General Motors turn over reams of documents and other data showing what the company knew when about a dangerous ignition problem that has been linked to 13 car-crash deaths.

The National Highway Traffic Safety Administration is investigating how GM handled the problem, which triggered the global recall of 1.6 million older-model compact cars. GM has acknowledged it knew of the ignition troubles a decade ago but didn’t recall the cars until last month.