King County authorities stated that over time, both sons had taken "more than 0,000 from Rule..of whom demanded money while she 'cowered in her wheelchair'," authorities said.
Michael Rule, 51, is charged with first-degree theft and forgery.
According to an April 2015 Huffington Post article, Rule had been in declining health since October 2013 as a result of her broken hip.
The King County Prosecuting Attorney's Office records noted at that time that she "is on oxygen at all times" and was suffering from "extreme confusion" as well as being "vulnerable to undue influence" and "is unable to perform many activities of daily living without assistance".
In 2003, Rule's publisher released Heart Full of Lies, a book about Liysa Northon, who maintains she was a battered spouse and shot her husband in 2000 to protect herself and her children.
Rule's book suggested Liysa Northon premeditated the killing and faked evidence of abuse.
During the investigation, Rule stated, "Mike often goes into rages, where he throws things across the room and sweeps a counter clean with his arm." Authorities also stated Andrew Rule had been aggressive when trying to get money from Rule during 2014, including threatening suicide, and screaming obscenities at her.
Rule was granted an order of protection against Andrew Rule in January 2015.
Rule was also known for her book Small Sacrifices, about Oregon child murderer Diane Downs.
Many of Rule's books center on murder cases that occurred in the Pacific Northwest and her adopted home state of Washington.
Her first book, The Stranger Beside Me, is considered one of the most definitive biographies of Bundy, and was written under her own name, rather than the pen name she had previously used.