Already wounded by a shotgun blast to the back, a screaming Karen Shumey was crouched down with her hands over her ears when her son shot her a second time, causing massive injuries to her head and hands, witnesses testified Wednesday.

As a prosecutor showed jurors a photo of the victim’s lifeless body, lying in a pool of her own blood, her accused killer – Christopher Shumey – stared at the photo for several minutes but showed no outward emotion. Afterward, he whispered to himself.

His attorney, Pierre Blahnik, said Shumey, 36, of San Luis Obispo, was legally insane when he gunned down his mother, a 65-year-old schoolteacher from Arroyo Grande, on Sept. 17, 2011. The two had bickered at Christopher Shumey’s apartment earlier in the day, but his mother left so he could cool off. When she returned, he shot her twice as she stood on the balcony of his second floor Beach Street apartment.

During Wednesday’s testimony, a forensic pathologist and an evidence technician revealed the devastation caused by a 12-gauge shotgun, backed by photos of amputated fingers and a separated skullcap.

Karen Shumey would have survived the first slug, which entered her back, exited her lower abdomen and traveled through her left forearm, said pathologist Gary Walter.

“The slug failed to hit or lacerate any major arteries,” he said.

In previous testimony, a neighbor testified that Karen Shumey screamed “No!” and “I’m shot!” after the first shot. As alarmed neighbors began to come out of nearby houses, Christopher Shumey allegedly opened his front door and fired again, this time aiming at his mother’s head.

Based on his examination of the crime scene, John Lehr, an evidence technician for the San Luis Obispo Police Department, said Karen Shumey was crouched down and covered her head when the second slug hit her on the left side, causing massive wounds to her brain.

“All that was left was the cerebellum and brain stem,” Walter later testified.

If the defendant is found guilty, numerous psychiatric witnesses are expected to testify in the second phase of his trial, which will determine if he was sane at the time.