Solanki was arrested by CBI on Tuesday and was brought to the city yesterday on transit remand.
CBI lawyer Kumar Rajat today sought his 14-day custodial remand for further interrogation.
Additional Chief Judicial Magistrate H G Pandya granted remand of four days. Solanki would be examined by doctors during the period, the court directed.
The CBI lawyer argued that there was enough evidence showing Solanki's involvement in the murder conspiracy.
Solanki's counsel Nirupam Nanavati opposed the CBI plea and said the MP was being targeted because he belonged to "a certain political party", and was from Junagadh.
Jethwa had filed several RTI applications and a public interest litigation on the issue of illegal mining in Gir forest region, the last surviving abode of the Asiatic lion.
After the Gujarat police's crime branch gave a clean chit to the MP, Jethwa's father approach the Gujarat High Court. The High Court termed the police probe as "far from fair, independent, bona fide or prompt", and transferred the case to CBI.
