Alleged is an adjective:
Said, without proof, to have taken place or to have a specified
illegal or undesirable quality:
In that sentence, it correctly modifies attacker as an adjectival use of the past participle form:
mid-15c., "quoted," past participle adjective from allege.
Attested from 1610s in sense of "brought forth in court;" 1670s as
"asserted but not proved."
The adjectival use of verbs is quite common as you will find in this link.
As a third party news report in the public realm, inserting the adjective alleged is a professional practice to protect the author and publisher from legal liability. Though she did not plead with her alleged attacker, but with her attacker, the news reporter is prohibited by professional ethics and liability from communicating that assumption to the public, and the simplest linguistic insertion of alleged is a ubiquitous CYA technique in journalism.
The obviously logical:
- Bleeding profusely, she pleaded with the attacker, Mushataq, to take her to a hospital.
is transformed by liability considerations to:
- Bleeding profusely, she pleaded with the alleged attacker,
Mushataq, to take her to a hospital.
Normally, people ignore the insertion, but from time to time, pedants make hay from the humorous ambiguities the added word can imply.