Why did the Baltimore County Police hand the case over the Baltimore City Police (BPD)?

I’m trying to un-package a pretty crazy hypothesis. The crux of which is why BPD took the case away from the county in the first place. Like they didn’t have enough unsolved murders? The county police would have been more than qualified to take a case involving some petty high school romance-gone-wrong bullshit.

The implication being that there was a bigger case in play that incentivized BPD to take this case with the sole purpose of making sure Jay walked as a bargaining chip in a more important case to the cops involving Jay’s people.

Maybe it’s a simple issue of jurisdiction, but the county has their own homicide unit… so why did BPD want the case?