“I had previous affairs,” Banfield told jurors. 4 Brendan Banfield is taking the rare step of testifying in his own defense against charges he killed his wife Christine Banfield. 4 Brendan Banfield allegedly plotted to kill his wife after starting an affair with their au pair. 4 Banfield’s alleged nanny mistress Juliana Magalhães testified earlier this month about Banfield’s elaborate murder plot. Brendan then shot Ryan with his service gun to make it appear as though he’d valiantly saved Christine’s life, Magalhães testified.