Who killed Kathy Halle?

How extensive did Law Enforcement look into the Bruce Lindahl lead? It appears that there certainly was a pattern; and it also appears that the number of missing womens cases declined greatly after his death in 1981?

Rumors have it from the 70's that the Halle case was drug related? In the Colliander case if I remember correctly Lindahl abducted her from the Northgate shopping center took her to his residence on the east side of Aurora, and she escaped after he fell asleep. Why wasn't she protected being only 2 days away from court? Lindahl was described by neighbors as a Jeckyll-Hyde type character. A nice guy around the neighborhood, and then who knows after that. The one thing that would break his pattern as a suspect would be the fact that his last victim was a male Waubonsee Valley student who was murdered by Lindahl in the Cress Creek apartments in Naperville. How that poor victim ended up with him there seems to be a mystery?