“Imprisoned for 38 years, supporters believe activist leader was framed for murder by police in tumultuous early ’70s.”
Oh dear. How would you interpret this headline?
It seems to imply the supporters were imprisoned for 38 years!
Adjectives that end with -ing and -ed are called participles.
When you use such participles with no proper subject, you could mislead others with your sentence.
This is not good writing and if you do that in your composition, your examiner may have a similar confusion.