Need advice on an LLC I invested in?

My last year of college, I invested 10,000 dollars in an LLC and was named a member on the initial paperwork. I never worked for the company and was only given periodic updates for the first year. I never took any profits from the company. I started my adult working life and went my separate way from any affiliation with the company. I have since learned that the person I started the LLC with opened up a credit card that was a business credit card that he personally guaranteed. He did not make the necessary payments and became delinquent on the account. He is claiming that they have garnished his wages and that I am responsible for half of the debt. He is saying that the cc company is threatening to sue him and the company to reclaim the debts. I have no access to any information on the credit card and have to take his word as to what is owed (24,000) and any action being taken by the bank. My question is this, am I responsible for this debt as a member of the LLC?