Nick Reiner has accused his siblings of backing out of an agreement to fund his legal costs in connection with his trial over the murder of their parents.

The 32 year old - who has pleaded not guilty killing filmmaker Rob Reiner and producer Michele Singer Reiner in December 2025 - filed a probate petition earlier this week to seek access to a $1.5 million trust fund established in his name by his mom and dad, and in the documents he hit out at older brother Jake Reiner and younger sister Romy Reiner, People magazine reports.

Nick wants to use the funds to re-hire attorney Alan Jackson, who first represented him after his arrest but was "forced to withdraw" after allegedly being told funding from his client's siblings "would not be provided", the documents state.

The lawyer originally "agreed to undertake the defense, subject to a retainer agreement and funding, with the siblings agreeing to act as third-party payors," and has written a letter in support of Nick's claims.

He wrote in his declaration: "Mr. Reiner's siblings participated in communications concerning the representation and agreed verbally to act as third-party payors for Mr. Reiner's defense.

"The family representative and family members assured me that the retainer agreement would be promptly returned and that the agreed-upon funds would be promptly paid.

"My decision to proceed was based on my understanding that Mr. Reiner had retained my firm and that the agreed-upon fee would be funded by third-party payors."

However, in late December 2025, a "family representative" involved in the negotiations allegedly told him "none of the anticipated third-party funding would be provided."

Alan continued: "That position was inconsistent with the prior assurances on which my firm had relied.

"Without an available source of funding, continued private representation by my firm was no longer feasible. My firm thereafter sought to withdraw in accordance with applicable court procedures and professional obligations."

Nick - who is currently being represented in the murder case by public defender Kimberly Greene - also had his attorney, Anita P. Wu write an email on his behalf to the trustee of the trust fund, in which she noted Alan's fees "were negotiated and agreed to by Nick's siblings on his behalf before they reversed that commitment."

Alan stressed in his declaration that he is "committed to representing" Nick and "willing to consider reasonable alternatives to the original fee arrangement."

The petition doesn't make it clear whether the original agreed-upon funding would have drawn from Nick's trust, other Reiner family trusts, or a different source.

And neither of his siblings have been publicly identified as one of the trustees of Nick's trust, who would have had to approve any distribution of funds.