In Freak the Mighty, what does the cop say that alludes to the fact that Max's dad is in prison?

In chapter seven, Max and Kevin join forces to escape the attack of Tony D. and his gang. With Kevin on Max's shoulders, Kevin does the thinking and directing while Max does the running. They end up running into the pond to get away from Tony's blade, but then the bullies start throwing rocks at the boys. Fortunately, Kevin can whistle loud enough to attract the attention of a cop car. The cop car shines a bright spotlight over the pond and discovers the boys. Eventually, the cops get ropes to assist in recovering the boys from the pond. The boys are given blankets and Cokes while also being told that they will keep an eye out for Tony D.--not to worry. Then, one of the cops asks for the boys' names so they can start calling mothers. When Maxwell tells them his name, one cop says the following:

"Hey, isn't that Kenny Kane's boy? Must be. Old Killer Kane, is he still inside?" (39).

There are two things that the cop says that help a reader infer that Killer Kane is in prison. First, the reference to the name "Killer Kane" references what Max's dad is accused of doing--killing someone. Then, the cops says "still inside," which can be inferred as meaning that Kane is still in prison. At this point in the book, the readers don't know much about Max's parents other than the fact that his mother had died. What the cop says not only gives information into the status of Max's father, but it is also a little bit of a foreshadowing that Killer Kane will be in the story at a future time. If Kane were not to be mentioned further in the story, then there wouldn't be much reason to mention him now; so, the reader's mind is primed for future events surrounding Killer Kane.