The resignation came amid recent allegations by Massachusetts' attorney general that the Boston archdiocese engaged in "an elaborate scheme" to keep quiet the issue of child sexual abuse by priests.
The resignation was caused by the allegations.
The resignation came amid the allegations but not necessarily because of the allegations. The system cannot decipher between amid and because of in this context.
( z1 cause :ARG0 ( z2 allege ) :ARG1 ( z3 resign ) )