simple past vs past perfect

[retro]

"...She then told a Sears associate, who announced over the intercom for Adam to meet his mother at one of the information desks. Revé later said that she had no confidence that Adam would be able to locate the desks. Adam and his mother were never reunited.

There are claims that a security guard threw the children out of the store for bickering over the video game, and perhaps Adam was confused and thought he had to leave too. Investigators think Adam had been mistakenly associated with a group of older children who were causing trouble and told to leave the shopping mall. It is suspected that Adam was abducted near the front exterior of the store after the other boys went on their way."

I wonder if "was" can be used instead of "had been" as it's clear that mistaking Adam happened first and afterward he was thrown out.

 

[2006]

"...She then told a Sears associate, who announced over the intercom for Adam to meet his mother at one of the information desks. Revé later said that she had no confidence that Adam would be able to locate the desks. Adam and his mother were never reunited.

There are claims that a security guard threw the children out of the store for bickering over the video game, and perhaps Adam was confused and thought he had to leave too. Investigators think Adam had been mistakenly thought to be associated with a group of older children who were causing trouble and told to leave the shopping mall. It is suspected that Adam was abducted near the front exterior of the store after the other boys went on their way."

I wonder if "was" can be used instead of "had been" as it's clear that mistaking Adam happened first and afterward he was thrown out.

Yes, "was" can be used.

 

[indonesia]

Does the above sentence need 'thought to be' in it?
I have read it several times and it seems a bit of a mouthful. Is it possible to exclude it? or would you recommend it stays?

 

[2006]

Does the above sentence need 'thought to be' in it?
I have read it several times and it seems a bit of a mouthful. Is it possible to exclude it? or would you recommend it stays?

The addition of "thought to be" more clearly expresses the intended meaning.
The investigators don't think that Adam had by mistake associated with a group of older children; they think the security guard mistakenly thought he was associated with the older children.