NDP MP Jenny Kwan also expressed disappointment in Johnston's decision not to recommend a public inquiry.
"I think there are a lot of unanswered questions that we're still waiting for," Kwan said.
Unlike Chiu, Kwan said she was able to meet with Johnston, but only because NDP Leader Jagmeet Singh invited her to join him in his meeting with the special rapporteur.
Kwan said she was also contacted by the Canadian Security Intelligence Service (CSIS) after the federal government expelled a Chinese diplomat for allegedly targeting the family of Conservative MP Michael Chong.