Broken glass cannot penetrate the monster's petrified skin, yet he can be given a shot with a hypodermic needle.-----Dr Rogers, having read Cooper's diary, tells Carol and Tracy that Eric, Dr Murdock and the others can be hurt; it's only when their vital energy is running out that they become stonelike. After an energy transfer, they go along like anybody else for months or years (with Eric, now reduced to hours). Eric received the injection immediately after an energy transfusion.
Dr. Rogers attempts to do an autopsy, which is interrupted. It is very unusual for a psychiatrist to do an autopsy. Only a forensic surgeon would attempt such.
Dr Rogers is only doing the autopsy because he has been refused permission by the prison authorities to send the body for autopsy to the proper people. Since he believes that the death is suspicious, he examines the body in secret as his only option for finding evidence.