We need a verb that logically connects 'new findings' with a 'theory'. 'Collaborate' means to work together, which is not applicable here. 'Collide' means to crash into, which makes no sense in this context. 'Collude' means to conspire or plot in secret, which also does not fit. 'Corroborate' means to confirm or give support to a statement, theory, or finding. The sentence logically means that the new data supports the theory of suicide.