Suspension

When a public officer is on trial in a criminal case under either RA 3019, the Revised Penal Code or related laws, can be suspended while the case is ongoing. If convicted by final judgment, he loses all his retirement and gratuity benefits. If acquitted, he will be reinstated and the salaries an all other benefits due him during the period of trial will be paid to him (unless administrative charges were filed against him while the criminal case was pending.)

Suspension, though mandatory, isn't automatic. The official in question is still entitled to a hearing that is required to determine the validity of the accusations against him because of his right to due process. Only when it is determined during the hearing that suspension is proper that an order for suspension will be issued. Therefore, a suspension may or may not be put into effect while an official is on trial; it all depends on the findings of the pre-suspension hearing. 

In Santiago vs. Sandiganbayan (GR128055, April 18, 2001) there are 3 specific arguments given as to why a pre-suspension hearing is required, since due process is too broad a justification:

1.) Whether or not he was given the right to a preliminary investigation

2.) Whether or not the acts complained of constitute a violation of RA 3019 or related laws

3.) Whether the grounds for a motion to quash under Rule 117 of the Rules of Court are available to him

It is curious to note also that, under the wording of sec. 13 of RA 3019 itself, lifting of suspension requires an acquittal. If the case is dismissed, there is no acquittal and therefore the official will remain suspended.

Suspension by nature is not considered a penalty because the suspended official will be entitled to reinstatement and unpaid benefits if he's acquitted. It is, instead, a preventive measure aimed at keeping the official in question from making use of his powers to frustrate the investigation (intimidation, etc.) It is therefore not considered ex post facto. 

Suspension also can't be indefinite; to do so would constitute another violation the official's right to due process. The period of suspension will vary according to which branch of service the public officer belongs to. Also suspension of a member of Congress follows rules that are different from those of public officers from other branches of government.