HOUSTON (AP) — An Alabama man condemned for a 2006 robbery-slaying in the Texas Rio Grande Valley has won a new punishment trial after Texas' highest criminal court has thrown out his death sentence.

The Texas Court of Criminal Appeals has ruled 5-4 Wednesday that trial attorneys for 47-year-old Douglas Armstrong conducted a constitutionally inadequate investigation when they presented jurors their case for why Armstrong should not be given a death sentence. A Hidalgo County jury decided on the death penalty after convicting him of the fatal slashing of Rafael Castelan in Donna in South Texas.

The court says a more thorough investigation of Armstrong's "squalid and dangerous home life" and expert testimony about his mental and physical health issues may have convinced at least one juror to choose a life sentence.