Yes, the president can be indicted, but it's not likely

As Rebeccas Buckwalter-Poza explains there is no logical or legal resaon why a president shouldn't be indicted. The problem is that the Department of Justice has a long history of declaring otherwise and you would have to find a judge, District Court and Supreme Court to go along with it. This is one more sign of the end of the First American Republic. 

Rebecca Buckwalter-Poza,  Daily Kos  There’s no line in the Constitution, case from the Supreme Court, or federal law to say that the president can’t be indicted. Rather, the closest we’ve gotten from the Supreme Court—Clinton v. Jones, in 1997—was a unanimous vote that the president can be sued and subject to a civil trial while in office. The justices found the potential disruption to the presidency wasn’t unconstitutionally burdensome. Nor would it be in the case of a criminal trial.

... The Office of the Special Prosecutor investigating Nixon concluded in 1974 that Nixon could be, even had to be, indicted at the conclusion of its investigation. One of its strongest points, relevant here, is that a grand jury has a sworn, constitutional duty to “present” all offenses that come to the jurors’ knowledge. If a grand jury considering someone else’s indictment has evidence implicating the president, are they supposed to ignore it? Then there’s that thing about the “paramount importance of reaffirming the integrity of the law.” The authors also note, apropos of DOJ’s argument, that indictment and prosecution are less disruptive to government than impeachment.

Independent Counsel Ken Starr reached the same conclusion in May 1998. He leans on a few key, common sense arguments: No one’s above the law. The Constitution doesn’t grant immunity. A criminal proceeding wouldn’t supplant the impeachment mechanism. Finally, it’s nuts to think impeachment must proceed prosecution; that would put Congress functionally in charge of when an executive power can be exercised, violating the separation of powers.

The best writing on the subject comes not from DOJ or a counsel of any sort but from the judiciary—the U.S. Court of Appeals for the District of Columbia—in a case over what Nixon could be made to turn over to a grand jury. The 1973 opinion, which Nixon did not appeal, shreds the claim that the president isn’t indictable.