Her attorney Gordan Preglej said Culjak was also suspected for abuse of office in the Core Media case.
She is the last to be investigated after the prosecution last year began probing her former husband Vladimir Selebaj and four other persons for the syphoning of more than HRK 16 million from the Core Media and Media Spot companies and for HRK 3.1 million VAT evasion.
Preglej said he would appeal Zagreb County Court Judge Vera Polak Presecki's decision on one month's investigative prison.
According to unofficial reports, Culjak was arrested and imprisoned after asking two witnesses, having learned that she was under investigation in the Core Media case, to change testimonies that were not in her favour.
Preventing the collection of evidence carries a prison sentence of one to eight years.