Remember that in some states in the United States, you need to invoke the 5th amendment before you have the right to remain silent. Otherwise, your silence can be used against you.
Say a simple phrase like: "I invoke my 5th amendment rights to silence, and I would like to contact to an attorney."
From: https://www.nolo.com/legal-encyclopedia/when-how-invoke-your-right-silence.html
You Can't Be Silent If You Want to Be Silent
In a closely contested 2013 decision, the U.S. Supreme Court held that prosecutors can, under appropriate circumstances, point to an out-of-custody suspect's silence in response to police questioning as evidence of guilt. (Salinas v. Texas, 133 S. Ct. 2174 (2013).)
Using Evidence of Silence to Prove Guilt
According to the Court, the prosecution can comment on the silence of a suspect who:
is out of police custody (and not Mirandized) voluntarily submits to police questioning, and stays silent without expressly invoking his Fifth Amendment rights.
The only way to prevent the government from introducing evidence of the suspect's silence at trial is to explicitly invoke (assert) the right to say nothing. In other words, without being warned by the police or advised by a lawyer, and without even the benefit of the familiar Miranda warnings (which might trigger an "I want to invoke my right to be silent!"), the interviewee must apparently say words to the effect of, "I invoke my privilege against self-incrimination."