Investigators found notebook detailing shooting plans and 'shrine' to past killings in home of accused Georgia mass killer / DNA from Georgia woman's murder leads to wrong twin, investigator says: 'Crime of opportunity' / Georgia investigators looking for answers on school shooter's access to gun, motive / Investigators say crime lab improvements aided arrest of Alabama man in 24-year-old Georgia murder / Georgia man killed girlfriend, disposed of body with family help after she discovered secret marriage: police / Arrest made in 2001 murder of Georgia law student found dead in burning home / Authorities make arrest in 2001 killing of Georgia law student who was found dead in a burning home / Man gets 4 death sentences for kidnapping, rape and murder of 5-year-old Georgia girl / Georgia mom found guilty of murder after allegedly attempting to kill daughter's alleged child molester