Short answer. Yes. A partner who knew about the dissolution and continued contracting in the firm's name is not protected by the general rule that requires co-partners to share liability. That exception applies only to a partner who acted without knowledge of the dissolution.
What the law says
the partner acting for the partnership had knowledge of the dissolution
Civil Code, Article 1833 — Liability Among Partners After Dissolution. Read the full provision →
The general rule and why it does not help your partner
Article 1833 of the Civil Code addresses liability among partners when dissolution is caused by the act, death, or insolvency of a partner. The general rule is that each partner remains liable to the others for their share of any liability created by a partner who continued acting for the firm as if the partnership had not dissolved. But the article carves out an exception: that shared liability does not arise if the partner acting for the partnership had knowledge of the dissolution. A partner who knew — as your partner did — and still contracted in the firm's name falls squarely outside that protection.
Knowledge is the dividing line
The key distinction Article 1833 draws is between a partner who acted in ignorance and one who acted in full knowledge. A partner who genuinely did not know the dissolution had occurred and contracted in the firm's name while still believing the partnership was alive has a stronger position — the co-partners may still share the resulting liability. But once a partner has knowledge of the dissolution, the policy protecting innocent action no longer applies. Continuing to deal in the firm's name after that point is a knowing act, and the consequences fall on that partner personally.
When dissolution is by death or insolvency
The article draws a parallel rule for dissolution caused by a partner's death or insolvency. In those cases, a partner who acts for the firm remains within the general liability-sharing framework unless the partner acting for the partnership had knowledge or notice of the death or insolvency. The standard is slightly different — either actual knowledge or notice is enough. This reflects the reality that news of a death or insolvency may spread informally and quickly, and it would be unfair to require formal notice before holding a partner accountable for continued dealings.
What this means for you and your co-partners
If the partner who continued contracting after the voluntary dissolution did so with knowledge of that dissolution, you and the other co-partners are not obliged to absorb their share of the liabilities created by those post-dissolution contracts. The responsibility for those consequences lies with the partner who acted after the dissolution, not with those who had already wound down their participation. Documenting when dissolution occurred, and what each partner knew at the time, is important if these liabilities are contested.