(AP) — Detectives in Northern California are trying to get a DNA profile on the Zodiac Killer to find him with the family-tree tracing technology investigators used to make a recent arrest in another decades-old case.

Vallejo police Detective Terry Poyser tells the Sacramento Bee his agency has submitted two envelopes that contained letters from the Zodiac Killer for DNA analysis.

The recently developed technology was used to arrest Joseph DeAngelo, the alleged Golden State Killer.

Poyser says the department is working with a private lab to try to obtain a full DNA profile from saliva on the envelopes’ flaps and stamps. Results are expected in the next few weeks.

The Zodiac Killer killed five people in Northern California in 1968 and 1969. He sent taunting letters and cryptograms to police and newspapers that included astrological symbols.