While a paucity of serotonin correlates somewhat with depression / suicide, there is a faction concerned that treatment with SSRIs may lead to impulsive behavior, including suicide.

Several lawsuits involved a depressed person who was so disfunctional that they could not arrange their own ideated suicide; they gained enough energy (post-SSRI prescription) to hit the pawn shops.

It makes some sense: excess serotonin causes agitation. SSRIs increase serotonin around the receptor cells (which have adjusted to the low levels) causing a temporary, relative overdose.

Much more in the way of facts and hype in the book PROZAC: PANACEA OR PANDORA?