Family Law San Antonio: Lawyers and Paralegals | Tessmer Law Firm
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Tessmer Law Firm, P.L.L.C. is owned and operated by Heather Clement Tessmer, attorney at law. She has over 20 years of experience practicing law. Heather graduated from St. Mary’s University Law School and began her career as an attorney in 1999. In 2001 she relocated with her family to San Angelo, Texas, where she opened her own office. In 2005, Heather moved back to the San Antonio area, opening her first office in Fair Oaks Ranch, Texas. Since 2005, Tessmer Law Firm has been continuously growing and is now headquartered at the Northwest Center building in San Antonio, Texas.


We have evolved into a “full-service” firm – assisting clients through every facet of legal representation in family law, estate planning, and personal injury cases.

Heather Clement Tessmer

Board-Certified Family Law Attorney

Heather Clement Tessmer began her legal career in 1999 after graduating from St. Mary’s University School of Law. In 2001, Heather opened her own office and began accepting cases from a diverse clientele. In January of 2010, the office evolved into Tessmer Law Firm, PLLC.  Heather continues to offer quality legal services to San Antonio and the surrounding Hill Country.


  • J.D., St. Mary’s University School of Law (1999)
  • B.B.A, Angelo State University(1989)
  • College of the State Bar of Texas – Maintaining at least 30 hours of CLEs since 2009


Certified Mediator

  • Basic mediation training
  • Family Law mediation training

Admitted to the Bar

  • State Bar of Texas (1999)
    • Women in the Law
    • Family Law
    • Collaborative Law
    • Alternative Dispute Resolution
    • General Practice
  • Federal Bar
    • Eastern District (March, 2010)
    • Western District (December, 2010)
    • Southern District (December, 2011)
    • Northern District (January 2012)


  • San Antonio Bar Association
  • Bexar County Women’s Bar Association
  • Kendall County Bar Association
  • Fellows of the Texas Bar Foundation
  • St. Mary’s University School of Law Alumni
  • Alamo Area Mediators Association
  • Texas State Bar College

Casey Lee

Senior Associate Attorney

Casey Lee is a Senior Associate Attorney with Tessmer Law Firm, P.L.L.C. Casey earned her law degree in 2015 from Catholic University of America, Columbus School of Law in Washington, DC. Upon graduation, Casey served for two years as the Judicial Law Clerk to the Presiding Judge of the Superior Court of the District of Columbia’s Domestic Violence Division.

While in law school, Casey was the Senior Student Articles Editor of the legal periodical, The Journal of Contemporary Health Law and Policy. At graduation, Casey received the Clinical Legal Education Association Outstanding Clinical Student Award.

Casey is a proud alumna of College of the Holy Cross in Worcester, Massachusetts. After graduating from college in 2010, Casey joined Teach For America and spent two years teaching second grade and then kindergarten in a low-income community in Dallas, Texas. Casey’s time in Teach For America is what inspired her to dedicate her career to the practice of Family Law.

Casey is a native Texan and is a member of the State Bar of Texas. Casey is the current Community Service Co-Chair of the Bexar County Women’s Bar Association. Casey was also a member of the 2019 Bexar County Women’s Bar Foundation LEAD Academy Class. In 2019, Casey was named a Top Young Family Law Attorney by San Antonio Magazine and one of San Antonio’s Best Family Law Lawyers by S.A. Scene Magazine in 2019 and 2020.

Casey’s favorite thing about working for Tessmer Law Firm:

“I love my job. I get to work every day with a team of bright, strong, and passionate women who share my dedication to successfully advocating for our clients and our clients’ families.”

Katherine Flores

Associate Attorney

Katherine Flores joined Tessmer Law Firm as an Associate Attorney in October of 2019. Katherine earned her Juris Doctorate from St. Mary’s University School of Law in December 2018. While at St. Mary’s, she earned two scholarships and was on the Dean’s List. Prior to attending law school, Katherine worked in the Financial Benefits department for a local corporation. Katherine practices family law, wills and estates law, and general civil law.

Katherine is inspired by her family. She has been married to her husband, Adrian, for twenty years. They have two beautiful daughters and sixteen nieces and nephews. Being surrounded by so many loving children, she is often reminded to enjoy the little things in life and that resilience is key.

Katherine’s favorite thing about working for Tessmer Law Firm:

“I’m happy to have been welcomed by Tessmer Law Firm with open arms. I enjoy this culture in which everyone is offered unique opportunities to learn and grow.”

Mariana Posadas

Associate Attorney

Mariana graduated from Texas A&M University of Corpus Christi where she received her bachelor’s degree in 2016 with Cum Laude honors in Criminal Justice. Mariana’s concentration of study involved domestic violence and juvenile justice. After receiving her bachelors, Mariana moved to San Antonio to attend law school at St. Mary’s University School of Law where she graduated at the top of her class, with Cum Laude honors. During her law school career, she was a law clerk at several law firms and organizations in San Antonio. Born and raised in El Paso Texas, Mariana is a fluent Spanish speaker. In her free time, Mariana attends boxing classes and plays competitively on a volleyball team with her fiancé. She also enjoys taking her dog Phoebe on long walks.

Mariana’s favorite thing about working for Tessmer Law Firm:

My favorite thing about working at Tessmer Law Firm is being surrounded by strong, independent women who inspire me everyday. Everyday I come to work I am challenged. I love being a strong and powerful advocate for all our clients.”

Elaine Simons

Director of Legal Services/Senior Paralegal

Elaine Simons began working for Tessmer Law Firm in April 2015. She has an Associate Degree in Business Education. Prior to joining our team, Elaine worked in Sales and Marketing for 24 years. Elaine joined our team as a Receptionist and soon became a Legal Assistant. While completing her Paralegal Program at UTSA, she joined the San Antonio Paralegal Association as their first-ever Student Liaison. In addition to that position, she has served on the board of SAPA as Secretary in 2019-2020 and is currently the 2020-2021 President-Elect.

Elaine was nominated for Paralegal of the Year in October 2019 by her peers. She is currently the Director of Legal Services/Senior Paralegal of Tessmer Law Firm.  She is also an active member of both the National Association of Legal Assistants and the State Bar of Texas Paralegal Division.

Elaine was born in New Braunfels and currently lives in San Antonio.  She is passionate about animals and enjoys volunteering in the community with a variety of non-profits.

Elaine’s favorite thing about working for Tessmer Law Firm:

“From the moment I joined the team, I have felt like family. Even though I did not have a legal background, I have been fortunate to learn from the best in the field. Each person has taken me under her wing, helping to make me the best I can be. Everyone is very encouraging, and we all pull for each other. Most importantly, we consider our clients as family. We take pride in what we do and want only the best for our clients.”

“Don’t Follow Your Dreams…..Chase Them!”

Jacqueline Cisneros

Financial Director

Jacqueline Cisneros began working for Tessmer Law Firm in July 2014. In 2020, Jacqueline was named the Financial Director of Tessmer Law Firm. She is a San Antonio native and a devoted mother of four beautiful children. When not working and caring for her family, Jacqueline enjoys cooking, traveling, and embracing all of the wonderful San Antonio culture.

Jacqueline’s favorite thing about working for Tessmer Law Firm:

“It is hard to pick just one thing I love about working for Tessmer Law Firm because there are so many. I love the family atmosphere fostered by my coworkers and how we extend that to our Clients. I look forward to coming to work every single day. It truly is such an inspiration to work beside such strong women!”

Marissa Brady

Legal Assistant

Marissa Brady began working for Tessmer Law Firm in July 2020 and is originally from Wilkes-Barre, Pennsylvania. Marissa received a Bachelor of Liberal Arts degree from Temple University in Philadelphia, Pennslyvania and completed the Paralegal Certification Program at The University of Texas at San Antonio.

Marissa loves the outdoors and during her free time, loves to cuddle her two greyhounds and mountain bike with her fiancee. Her favorite quote is, “the biggest risk is not taking a risk.”

Marissa’s favorite thing about working for Tessmer Law Firm:

“Every day is an opportunity to learn something new. I enjoy the team atmosphere and working closely with one another. I am thankful for the opportunity to be a part of the Tessmer Team, and I look forward to my future here.”

Kristen Peeler

Legal Assistant

Kristen began working for Tessmer Law Firm in July 2020. Kristen received her Paralegal Certification from the University of Texas at San Antonio and is currently earning a Bachelor of Arts in Communications. Kristen is also a Member of the San Antonio Paralegal Association.

As a native to San Antonio, Kristen’s favorite things to do in her spare time are walking her dog, Yue, around The Pearl, and finding the best coffee shops San Antonio has to offer (even if she already had plenty that day). Kristen can also be seen filming commercials or voice-over work on the side in Austin, Texas as an actor with Pastorini-Bosby Talent!

Kristen’s favorite thing about working for Tessmer Law Firm:

“I love learning new things! This industry fascinates me and to learn from so many amazing mentors is an honor.”

Ariel Erwin

Law Clerk

Ariel began working for Tessmer Law Firm in August 2020. Ariel is originally from San Angelo, Texas. She attended Angelo State University where she studied International Business with a minor in Technical Writing and graduated in 2012 Magna Cum Laude with honors. Prior to working at Tessmer Law Firm, she worked in human resources for about five years. Ariel began attending St. Mary’s School of Law in 2018. She has been on the Dean’s List every semester it has been published! Ariel was also a Staff Writer for the St. Mary’s Law Journal and is a member of the Women’s Law Association. Ariel is very excited to graduate in May of 2021.

Ariel’s favorite thing about working for Tessmer Law Firm:

“I love being a part of the Tessmer Law Firm family because I get to work with a group of empowered and intelligent women.”

Jordy Hernandez


Jordy Hernandez began working for Tessmer Law Firm in September 2020. Jordy is a Texas native— she was born in Austin and grew up in San Antonio! Jordy is currently earning her degree in Business Management at the University of Texas at San Antonio.

In her free time, Jordy enjoys walking her dog at the Pearl or San Antonio River Walk. She also enjoys cooking. Her favorite part about cooking is getting to eat the meals she creates. Jordan expresses her creative side through astrology, painting, and reading.

Jordy’s favorite thing about working for Tessmer Law Firm:

“My favorite thing about being at Tessmer Law Firm is the women empowerment. I love that it is female-led and appreciate all of the support from the women in the office.”