brian had even seen in the paper that they were calling him a crazy and deranged neighbor. it just devastated him. >> reporter: that summer, brian tate tumbled into a downward spiral and never recovered. he died in september, 2012, just four months after lisa's murder. the coroner would think it was heart. >> yes. >> reporter: what does the family think it was? >> a heart. a broken heart. >> reporter: now the prosecutors from the state's attorney general's office worried that a jury might think the deranged deceased neighbor did it. their plan had been to call tate as a witness. >> on the theory that the devil you know is always better than the devil you don't, we wanted the jury to see mr. tate. >> reporter: but now with a trial date approaching, prosecutors had lost a key witness. >> bad for us, good for them. it's great for them. >> reporter: the long-awaited murder trail of seth techel was