Mohammed Abdul Kadir, 24, fled the UK thee days after Jalal Uddin, 71, was bludgeoned to death in Rochdale, in February, Manchester Crown Court heard.
It is alleged the imam was murdered by Mr Kadir and Mohammed Hussain Syeedy who "hated his form of Islam".
Mr Syeedy, 21, of Ramsay Street, Rochdale, denies murder.
The Crown said Mr Uddin was attacked by Kadir as he walked through a children's play area in Rochdale, on 18 February.
The prosecution said Mr Kadir, of Chamber Road, Oldham, boarded a flight from Manchester to Copenhagen, Denmark, on 21 February and from there flew to Istanbul.
His whereabouts are unknown although it is thought he may have travelled onwards to Syria, the jury was told.
Mr Syeedy is alleged to have acted as the getaway driver on the night of the attack with the prosecution saying he knew full well that Kadir intended to kill or seriously harm Mr Uddin.
The court has been told the pair "hated" Mr Uddin, a Bangladeshi national, after discovering he practised Ruqya healing, which involves the use of amulets to bring good luck to the wearers.
The jury heard that IS considered such practises as forbidden and that the terror group had beheaded magicians.
Expert witness, Robert Gleave, professor of Arabic studies at the University of Exeter, told the court some fabric patches for clothing and flags found in Mr Syeedy's bedroom - some with images of a Kalashnikov rifle - had jihadist connotations.
And he added some were "almost exclusively associated with Isis".
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The trial continues.
One of two supporters of the so-called Islamic State (IS) group accused of murdering an imam, is believed to be in Syria, a court has been told.