Amber Heard Claims Cops Missed Key Evidence in Alleged Beating

Amber Heard is getting trashed because cops didn't do their job properly, or even worse lied to protect Johnny Depp ... so claims sources connected to the actress.

The sources say Amber had visible marks on her face when 2 officers responded to the 911 call on May 21. They claim the officers either didn't see the marks or are lying to protect Depp. They say Amber's injuries became more pronounced as time went on ... especially a day later.

LAPD officials insist the 2 cops did indeed look for injuries and found none.

We contacted 2 doctors who routinely treat trauma injuries who both said an iPhone hurled at someone would cause immediate swelling and some discoloration. BTW, in addition to allegedly throwing the iPhone, Heard claimed in legal docs he pulled her hair, struck her and violently grabbed her face.

As for the officers claiming there was no evidence of any broken glass in the apartment ... our Heard sources say that's because Amber met the cops in an adjoining unit, and they never went to the one where the incident went down.

And Amber's sources say she's the only one who swore under oath her version of events were accurate. Amber's people say Johnny's team had 24 hours notice before the TRO was heard, and he never filed a sworn declaration.