I wouldn't
Personally, if I robbed a bank and was free in Mexico, I would never turn myself in. They will put you in jail for a long time!
The federal bank robbery statute, 18 U.S.C. 2113, provides in pertinent part:
"(a) Whoever, by force and violence, or by intimidation, takes, or attempts to take, from the person or presence of another any property or money or any other thing of value belonging to, or in the care, custody, control, management, or possession of, any bank, credit union, or any savings and loan association . . .
. . . . .
"Shall be fined not more than $5,000 or imprisoned not more than twenty years, or both.
"(b) Whoever takes and carries away, with intent to steal or purloin, any property or money or any other thing of value exceeding $100 belonging to, or in the care, custody, control, management, or possession of any bank, credit union, or any savings and loan association, shall be fined not more than $5,000 or imprisoned not more than ten years, or both; .
I'm not a legal professional, but my opinion is that you would receive at least 10 to 12 years in prison depending on the circumstances (weapons, prior convictions).
Also, FYI Police Officers can lie to you in order to get you to talk/turn yourself in. If you do decide to turn yourself in, talk to a lawyer before you give them any information! If you can't afford one, you will be provided one.