Los Angeles (CNN) -- The Los Angeles Police Department can have access to personal tape recordings between Charles Manson follower Charles D. "Tex" Watson and his late attorney that investigators believe might hold clues to unsolved killings, a federal judge in Texas ruled Tuesday.
U.S. District Court Judge Richard Schell ruled that Watson waived his right to attorney-client privilege in 1976 by allowing his attorney to sell the tapes for $49,000 to the man who co-authored Watson's memoir.
LAPD investigators want the decades-old recordings between Watson and his attorneys because they believe the tapes could shed light on unsolved killings involving the "family," as Manson's followers were called, according to court documents.
"We are continuing to monitor the case, and are prepared to send our detectives out to Texas to pick up the tapes as soon as they are available," LAPD Cmdr. Andrew Smith told CNN.
"It is our understanding that there is a 30-day window for appeal, and we will wait for that to time to transpire before we send our detectives to Texas."
The news of the judge's ruling came the same day that California Department of Corrections authorities said they arrested a Mason follower, accusing him of attempting to smuggle a cell phone to Manson at Corcoran State Prison.
For more than four decades, authorities have speculated the Manson family was responsible for the rampage that left pregnant actress Sharon Tate and six others dead, including Leno and Rosemary LaBianca.
Manson has claimed more people were killed, though he has repeatedly made fantastic claims that later turn out to be false.
Watson has long maintained there is nothing for authorities to gain with the recordings.
In a June 5, 2012, letter to CNN, Watson wrote: "There is nothing new on the tapes that was excluded from my book 'Will You Die For Me?' The book was co-authored to show delicate consideration when sharing the graphic details of the crime in order to show respect towards the families of the victims."
Watson, Manson and three others -- Susan Atkins, Patricia Krenwinkel and Leslie Van Houten -- were convicted of murder in the killings.
In the letter to CNN, Watson asserted that "there are no unsolved murders committed by the Manson Family."
The gruesome murders were chronicled in the best-seller "Helter Skelter." In the court ruling, the judge notes "Watson expresses concern that the contents of the recordings may be hurtful to the families of his victims in the Tate-LaBianca murders."
The tapes are about eight hours of recordings between Watson and his attorney from 1969, Bill Boyd of McKinney, Texas, according to court papers. Boyd died in 2009.
According to court documents, Watson waived his attorney-client privilege to the tapes in 1976, and his attorney received partial payment for his legal fees when he gave a copy of the tapes to Chaplain Raymond G. Hoekstra, who subsequently co-authored the book, "Will You Die for Me: The Man Who Killed for Charles Manson Tells His Own Story."
In court filings, Watson requested "that the Tapes not be turned over to the LAPD, because they are not a creditor to my late attorney Bill Boyd, God rest his soul" and "because repercussions of the motion have not been fully considered by all parties concerned.
Added Watson in court documents: "... this case is high notoriety, with much media attention. For this reason, special consideration should be made with who takes possession of The Tapes, so they will not be misused for purposes unintended by the court and that could be hurtful to the families of the victims."
In 2008, Watson wrote CNN that he was aware of no bodies buried in a remote Death Valley, California, site called Barker Ranch, the last hideout for Manson and his family, when CNN did a report about a corpse-sniffing dog visiting the site.
Watson, 66, was convicted of seven counts of first-degree murder and has been denied parole 16 times. He will be considered again in 2016, according to the California Department of Corrections.
CNN's Cristy Lenz contributed to this story.