what's mean "bust out the big guns"

[baskervilles]

what's mean of "bust out the big guns", I got it from this transcript:

--Cut from transcript CSI 5.18, David want process the body, but Catherine think it not ready---------------
DAVID PHILLIPS: Hey, Catherine, um, I was wondering if I ...

CATHERINE: Oh, I'm sorry, David. We're going to need to keep the bodies in
their original position for a while longer.

(Catherine collects the hair strands and puts them in a bindle.)

NICK: Yeah. Crime scene this messy, gotta bust out the big guns. You know
what I mean? (David leaves the room.)
---------------

[Robert B. Mercer]

I usually hear "bring out the big guns" instead of 'bust out the big guns,' but the meaning is the same:

This is a time to get more serious, use more tools, get more help, etc.

Me: "This is too heavy, I cannot lift it."
You: "Okay, this is a time to bring out the big guns. We can ask some friends to help."

Me: "I have a very, very, very hard English question for you."
You: "Okay, time to break out the big guns. Let me get my dictionary and schoolbook and workbook and I will try to answer your question."

Me: "I can do this job"
You: "No, it is too hard for you. I am going to get a better worker to do it."
Me: "Oh, time to break out the big guns, hmmm?"

[baskervilles]

Thank for your kindly help

[MW]

In the context of CSI it means to bring in the Crime Lab boss, the expert, the BIG GUN.