The chain of custody quote that you give is normal for a lab. And the lab does not know what the "chain of custody" was before it got there. The prosecutor will put up the other people who did something with the evidence before it got to the lab....
You lawyer will tell you all about this. And I hope this isn't your only defense.
Thanks for considering my response on AVVO. The questioner and any reader do not have an attorney-client relationship formed by our communications on this website. Advice given by me on this website is general advice based on partial information. You should not rely on any advice given without first hiring a lawyer in the area where the case is pending, and providing that lawyer with full information.
Chain of custody must be established by documentary as well as direct oral testimony at the trial. All proof or lack thereof can be dealt with then. GOOD LUCK and GOD BLESS! Jerry
I LEAVE THE MIRACLES TO GOD...HE LEAVES THE PRACTICE OF LAW TO ME!