Neither police nor courts have the authority to impound passports of accused involved in criminal cases as the power to do so is conferred exclusively upon Regional Passport Officers under the Passports Act 1967
Section 10(3) of The Passport Act, 1967 mentions the conditions that may lead to impounding of passports. The said provision of law is being reproduced herein below for easy reference:
(3) The passport authority may impound or cause to be impounded or revoke a passport or travel document,-
(a) if the passport authority is satisfied that the holder of the passport or travel document is in wrongful possession thereof;
(b) if the passport or travel document was obtained by the suppression of material information or on the basis of wrong information provided by the holder of the passport or travel document or any other person on his behalf; [Provided that if the holder of such passport obtains another passport the passport authority shall also impound or cause to be impounded or revoke such other passport
(c) if the passport authority deems it necessary so to do in the interests of the sovereignty and integrity of India, the security of India, friendly relations of India with any foreign country, or in the interests of the general public;
(d) if the holder of the passport or travel document has, at any time after the issue of the passport or travel document, been convicted by a court in India for any offence involving moral turpitude and sentenced in respect thereof to imprisonment for not less than two years;
(e) if proceedings in respect of an offence alleged to have been committed by the holder of the passport or travel document are pending before a criminal court in India.
(f) if any of the conditions of the passport or travel document has been contravened;
(g) if the holder of the passport or travel document has failed to comply with a notice under sub-section (1) requiring him to deliver up the same;
(h) if it is brought to the notice of the passport authority that a warrant or summons for the appearance, or a warrant for the arrest, of the holder of the passport or travel document has been issued by a court under any law for the time being in force or if an order prohibiting the departure from India of the holder of the passport or other travel document has been made by any such court and the passport authority is satisfied that a warrant or summons has been so issued or an order has been so made."
You can file an RTI to seek certain information about who has impunded your passport and take further action accordingly.