"Mistakes were made" is an expression that is commonly used as a rhetorical device, whereby a speaker acknowledges that a situation was handled poorly or inappropriately but seeks to evade any direct admission or accusation of responsibility by using the passive voice. The acknowledgement of "mistakes" is framed in an abstract sense, with no direct reference to who made the mistakes.
For further reading, see Mistakes Were Made (but not by me): Why We Justify Foolish Beliefs, Bad Decisions, and Hurtful Acts, by Carol Tavris and Elliot Aronson (reviewed at Amazon).
Mr. Topczewski's statment is included in Marie Rohde's story in today's Milwaukee Journal Sentinel, headlined Weakland spreads the blame.
At WTMJ-TV "NBC 4" More Weakland Deposition Video Released, by Mick Trevey and Katie DeLong
At WITI "Fox 6", Milwaukee Catholic Sexual Assault Scandal Unravels
At WISN-TV "ABC 12" Milwaukee DA Reviewing Clergy Abuse Deposition
At WDJT "CBS 58" Was Weakland following church orders?
(via SNAP Network)