<P> The episode `` Player Under Pressure '' was originally supposed to air in April 2007 as episode 19 , but was delayed in the wake of the Virginia Tech massacre , as the episode 's plot featured finding human remains on a college campus . The episode later aired in April 2008 as part of the third season , with new footage . The episode `` Aliens in a Spaceship '' introduces the storyline of the Grave Digger , an unresolved case . The Grave Digger would later return in the fourth season , when the team discovers its identity . Serial killer Howard Epps returns for two episodes , in which the team must discover more of his victims . </P>
<P> The episode `` Player Under Pressure '' was originally supposed to air in April 2007 as episode 19 , but was delayed in the wake of the Virginia Tech massacre , as the episode 's plot featured finding human remains on a college campus . The episode later aired in April 2008 as part of the third season , with new footage . The episode `` Aliens in a Spaceship '' introduces the storyline of the Grave Digger , an unresolved case . The Grave Digger would later return in the fourth season , when the team discovers its identity . Serial killer Howard Epps returns for two episodes , in which the team must discover more of his victims . </P>
when did the gravedigger first appear in bones
when did the gravedigger first appear in bones
The episode `` Aliens in a Spaceship ''
The episode `` Aliens in a Spaceship ''