Translation:I was reading about his murder in a newspaper.
We probably wouldn't use Present Perfect here. There is a subtle difference between the use of Present Perfect and Past Simple in this context.
When we introduce new information that we've just read or heard about, and we don't specify when, we often use Present Perfect, at least in British English, usually with "just". But Past Simple is also possible, especially when talking about hearing it (because you heard about it at a specific time):
"I've just read in the newspaper that Joe Bloggs has been murdered"
"I just heard on the radio that Joe Bloggs has been murdered".
But in Duo's sentence, the use of "his murder", tells us that the speaker isn't introducing new information, but answering somebody, telling them that they had read in the newspaper about the particular murder which the other person has just mentioned. They would subconsciously think of this act of reading as a past event, so would use Past Simple:
"Have you heard? Joe Blogs has been murdered"
(New information, unspecified time - Present Perfect)
"Yes, I read about his murder in the newspaper."
"Yes, I heard about it on the radio".
(Specific event of reading/hearing - Past Simple)
Past Perfect is also possible, but I think we'd use it in a slightly different way, in conjunction with a verb in Past Simple:
"I rang Joe Blogg's wife to say how sorry I was. I had read about his murder in the newspaper"