About Us

Mr. Kaminsky’s success in litigation comes from understanding human nature, knowing the case better than anyone else, and his unique ability to effectively communicate with the trier of fact.



Daniel Kaminsky (Dan Kaminsky) was born in Anaheim, California in 1971. He graduated college from Cal Poly Pomona (California State Polytechnic University) with a BS in Biology in 1995. He attended the University of San Diego School of law, a top tier school, graduating with honors (cum laude) in 1998. He received American Jurisprudence Awards in Constitutional Law and Professional Responsibility. He became licensed to practice law in 1998. He owned and operated his own law practice from 1998 until 2008. In 2007 He, his wife and children relocated to Fond du Lac, Wisconsin. Mr. Kaminsky became licensed in Wisconsin in 2007. He served four years as the elected District Attorney in Fond du Lac, Wisconsin, supervising a staff of 7 attorneys and a total of 15 employees. Under his direction the office improved its felony conviction rate from below 40% to 65%. He personally never lost a felony trial.

Mr. Kaminsky has experience in both jury trial and court trial work and has served as an arbitrator for the Better Business Bureau. He has also handled numerous appellate matters and argued cases before the Courts of Appeal.

Mr. Kaminsky also enjoys hunting, golf, and billiards. He is a member of Rotary and serves on the charitable board for Fond du Lac Festivals, Inc.


Roberta Walz-O’Leary is an associate attorney at Kaminsky Law, S.C. and has been a licensed attorney since 1988.  She is a graduate of John Marshall Law School, Chicago, Illinois where her education focused on Litigation.  In addition to being licensed to practice law in Wisconsin, she is also licensed in Illinois. 

Attorney Walz-O’Leary enjoys working with clients and their families advocating for clients in divorce including property division, legal custody and physical placement of children, child support, maintenance, and paternity cases as well as post-judgment revision of family law issues such as maintenance, custody and placement, or child support.   

She has committed herself to providing compassionate, empathic and comprehensive legal assistance balanced with a strong courtroom presence.  The attorneys at Kaminsky Law strive to work as a team, providing the benefit of multiple perspective to ensure the best outcome of all cases.

In addition to family law, Attorney Walz-O’Leary has experience as a prosecutor and defense attorney in traffic, OWI and criminal law matters. 

She is married and she and her husband have raised their two boys in Illinois, New Hampshire and finally Wisconsin.  It is one of her greatest joys to have seen them both off to college and beyond.

Outside of the office, she enjoys running, cooking, and being involved in the community.




Attorney Michael Tonn was born and raised near Fond du Lac, Wisconsin. He graduated from Horace Mann High School. He then enlisted in the Navy and was ultimately homeported in San Diego, CA, on board the U.S.S. Lake Champlain. After serving four years in the Navy he received an honorable discharge and relocated to Portland, Oregon. There, he obtained a Bachelor’s of Science in Political Science from Portland State University. He attended Willamette University College of Law, Salem, OR. In law school, Michael was a research assistant for Professor Paul Diller, wrote case reviews for Willamette Law Online, and was a member of the Willamette Journal of International Law and Dispute Resolution. He also worked as a law clerk for the Oregon Law Center (a legal aid organization) and the Willamette Business & Non-Profit Law Clinic. Upon graduation, Michael worked for the State of Oregon, first as a social worker, and then as a hearing representative, handling administrative law hearings on behalf of the Department of Human Services, Aging and People with Disabilities.

In December 2018, Michael returned home to Wisconsin. He then took and passed the Wisconsin State Bar exam obtaining his license to continue his career in Wisconsin. He begins his Wisconsin practice at Kaminsky Law, with an intent to focus on estate planning, as well as criminal defense.

Away from the office, Michael enjoys spending time with family and friends, fishing, and playing drums and guitar.