These are not allegations. The federal government requires nonprofit organizations to file an annual Form 990 that discloses the sources and allocations of all funding, as well as other information such as board members, highest paid staff members, etc. This form is public information, to be made available so that donors may monitor the use of their funds, as well as so that the federal government can ensure that organizations benefiting from tax-free status are complying with the obligations of maintaining that status.
Priests for Life has not filed a 990 since 2008. Rachel’s Vineyard, a sister organization under the Gospel of Life Ministries umbrella, has never filed one, and has had its nonprofit status automatically revoked for that reason, though it still seeks donations and tells donors, incorrectly, that their donations are tax-deductible.
Internal audits are no substitute for the public documents in question (an audit, even an independent one, simply certifies that no one is embezzling funds, which is not the accusation here), and PFL spokespersons have consistently dodged the question of why the organizations are not in compliance.
Here is a link to Charity Navigator, a website that provides donors with unbiased evaluations of the effectiveness of nonprofits, based on public information. You will note that Priests for Life receives a very low rating, not only for its noncompliance with public reporting laws, but also for the disproportionate amount of funds spent on promotion and fundraising in contrast to actual program-related activities.
charitynavigator.org/index.cfm?bay=search.summary&orgid=6438