While having a point in an investigative ability earns you clues, having a few points to spend can produce a number of benefits. An idea for an investigative spend benefit that may not fit in every campaign or with every GM is the ability to define facts about the scene rather than just discover them.
If your GM allows, you can spend points from an appropriate investigative ability to declare a fact about the scene. The broader or more significant the edit, the more points you have to spend. If the fact contradicts an established feature of the scene, the adventure, or the campaign, the GM is free to veto your spend, in which case you get the ability point back.
This lets players take a little more control over the world and may take some pressure off the GM to flesh out scenes. By leaving details light, they offer players opportunities to fill the void.
This option works well with aspects. The fact you declare should match both the investigative ability you spend as well as an aspect you can invoke. (Declaring a story detail is an established effect of invoking an aspect in Fate Core.)