。
She tried to dig into the truth behind the rumor.
Literal
She [topic-は] rumor [genitive-の] true-state [object-を] investigate-try did-attempt.
真相 ('the true state of affairs / the truth behind appearances') is a more nuanced word than 真実 ('truth' in the abstract); 真相 specifically points to the hidden reality behind a confusing or misleading surface — perfect for rumors, scandals, or mysteries. 調べてみる ('try investigating') uses ~てみる ('try doing'), and the volitional + と + した frame adds the 'attempt' layer: 調べてみよう ('let me try investigating') + とした = 'tried to attempt.' The two layers of attempt-marking (V-てみる + ~ようとする) suggest the action was undertaken but not necessarily completed — a hallmark of how Japanese carefully marks effort separate from success.