A few things of interest from this podcast.....
First, Peter Headley believes that Lisa's siblings who died "eating grass mushrooms" are the children who were seen with their mother in Rasmussen's car when he picked up a check in 1985. He also thinks that this woman may have been an "unofficial apartment manager" at a complex Ramussen had ties to in Fullerton or Anaheim.
The truck Rasmussen and Lisa were living in in the trailer park in California had Texas plates.
Finally, back when he was still married and living with his wife and kids in California, he began having an affair with a coworker. He convinced this woman to move into his family's home under the guise of being a live-in babysitter for his kids. When things got tense between the woman and his wife, he had the woman move to Colorado in an apartment he bought for her. Later (not sure how long), he told the woman to come back to California but she refused, since she was already settled with a job in Colorado. So Rasmussen flew down, persuaded the apartment manager to let him in to her apartment, and stole all of her personal belongings. After she reported him to the police for theft, Rasmussen left her alone.
Again, these all come from Det. Peter Headley via the above podcast.