Student or Learner
"The article of a famous journalist was the culprit of a huge scandal." OK?
The dictionaries I've checked relate "culprit" to a person, rather than a thing, as you say.
That having been said, though, we sometimes tend to personify objects.
An example might be when investigating the cause of, say, a plane crash, the investigators may well pinpoint the cause to a small, detailed component that failed. It's highly likely that they would say that they had "found the culprit".
Hope this helps
PS I wouldn't personally have used the word "culprit" in your example - I would have more likely said "trigger", as it appears to have been a natural follow-on rather than something that was found out later following an investigation.