Normally and in general, missing persons don't get much attention. Especially not the age group 14-18 years of age is often just declared as runaways. Admittedly, I stumbled with SK cases sometimes over the problem. You can read about Corll on my website is interested. But ...
1.) in a case involving a foreign national, the authorities of that country are may not as relaxed when their nationals disappear without explanation in another country. That causes political pressure and forces PDs to actually investigate a missing person case. And since most PDs have no resources for missing person cases, cases that have to be investigated got to for example robbery/homicide. Now, with two other countries having an eye on things, LSPD is under pressure and that gived motive to get rid of the pressure.
2.) LA and Orange County have developed some reputation in serial killer cases by working quick and effective, but I am not sure, how much this extends to other kinds of cases. However, those guys, who got themselves some success, came out of robbery/homicide there as well. That makes me think, the political pressure forced LAPD to send some of their best. The question that remains to me is, with what marching orders?