IF it was a STAFF MEMBER,ie someone who works on the property such as a maid, gardener, caretaker or even a female Secret Service agent there would be no reason to not list their name in the police report.
Which leads me to believe that the “witness” not named in the report was an Obama daughter.
"... As you will see, the Department has redacted dates of birth, addresses, social security numbers, medical information, and phone number of involved parties pursuant to G. L. c. 4, §7, cl. 26 (c), the privacy exemption. As you know, G.L. c. 4, §7, cl. 26 (c) exempts from public disclosure “personnel and medical files or information; also any other materials or data relating to a specifically named individual, the disclosure of which may constitute an unwarranted invasion of personal privacy.” Analysis under the second, privacy clause is subjective in nature and requires a balancing of the public’s right to know against the relevant privacy interests at stake. Attorney General v. Assistant Commissioner of the Real Prop..."
I neglected to mention that they would not have to say the witness was a “staff” member in the official report if she wasn’t. They had the discretion to leave the relationship unknown, merely someone who wanted to avoid publicity.