He said that "there is evidence that Cristiani was involved in the murder of the six Jesuit priests" which occurred on 16 November in San Salvador.
Cristiani murdered six Jesuit priests.
The paragraph states only that there is evidence that Cristiani was involved in the six murders, not that he did them.  This statement cannot be known and is neither correct nor incorrect.  The system has probably inferred too much from the paragraph, thinking that Cristiani's involvement must imply guilt.
( z1 murder :ARG0 ( z2 person :name ( z3 name :op "Cristiani" ) ) :ARG1 ( z4 priest :quant 6 :mod ( z5 religious-group :name ( z6 name :op "Jesuit" ) ) ) )