Officials said a city worker had discovered the scene

[Maybo]

Officials said a city worker had discovered the scene after hearing cries for help.
Emergency responders initially arrived at the scene at about 18:00 local time (23:00 GMT), San Antonio fire chief Charles Hood told reporters.
(Texas migrant deaths: At least 46 found dead in abandoned truck by Angelica Casas in San Antonio & Leo Sands)

Why did the writer use "had discovered" but not "discovered"?
Is it because the city worker had discovered the scene before the emergency responders or somebody else?

 

[dunchee]

Is it because the city worker had discovered the scene before the emergency responders or somebody else?

Yes.

 

[5jj]

Not necessarily. The past perfect would have been one possibility even if no emergency responders had arrived.

Officials said a city worker had discovered the scene after hearing cries for help. We have there a backshifted past tense in reported speech.

Incidentally, some native speakers would not backshift. They'd just say Officials said a city worker discovered the scene after hearing cries for help.

 

[Maybo]

Not necessarily. The past perfect would have been one possibility even if no emergency responders had arrived.

Officials said a city worker had discovered the scene after hearing cries for help. We have there a backshifted past tense in reported speech.

Incidentally, some native speakers would not backshift. They'd just say Officials said a city worker discovered the scene after hearing cries for help.

Did I get the grammar of backshift right?

Not backshift:
1. Officials said a city worker discovered the scene after he/she heard cries for help.

Backshifted:
2. Officials said a city worker had discovered the scene after he/she had heard cries for help.