The sketch comes nearly five months after the last piece of evidence was disclosed by a team of investigators comprised of local, state and federal authorities, including the FBI.
With those exceptions, police have remained tight-lipped, declining to release further evidence from German's phone or comment on the details of the girls' injuries.
Detectives have sifted through 18,000 tips and have interviewed at least 1,000 people as part of the high-profile double homicide investigation.
While several unrelated arrests have been made during the investigation, a suspect in the slayings has not been identified.
Meanwhile, a reward fund for information leading to an arrest has continued to grow, surpassing $230,000