A fourth and possibly final suspect allegedly involved in the kidnapping of six-year-old Amy'Leigh de Jager has been arrested, the national police commissioner's office confirmed on Monday.Police spokesperson Brigadier Vishnu Naidoo said in a statement on Monday evening, the 24-year-old was arrested earlier in the day "after a long search"."Members of the family violence, child protection and sexual offences unit that is tasked with the investigation arrested a 24-year-old-man today in Muvhango, an area just outside Vanderbijlpark."Naidoo said the man was expected to appear in court on Wednesday. He will remain in custody until October 1, when he will appear with the three other suspects for a formal bail application.READ: Teacher, co-accused fear for their lives, ask to be transferred from 'Sun City' prison"We are satisfied that we have all the people allegedly responsible for the kidnapping of Amy'Leigh behind bars and the possibility of more arrests being effected is very unlikely."The other three accused, Tharina Human, Laetitia Nel and Pieter van Zyl, appeared in the Vanderbijlpark Magistrate's Court on Friday for the continuation of their bail application.Only one of them has made a formal confession.During investigating officer Constable Clayton Motloung's cross-examination, it emerged Nel had made a formal confession after she was arrested.News24 previously reported Human, who is a Grade RR teacher at Laerskool Kollegepark, the same school that De Jager attends, was also a good friend of the De Jager family. Human allegedly cooked up the plan because she was in debt to drug lords, according to a WhatsApp voice note her father, Riaan Botha, had sent to a family member shortly after she was arrested.READ MORE | Amy'Leigh kidnapping: 5-year-old brother was initially grabbed, court hearsBotha has confirmed the authenticity of the voice note, which also relayed information that Human was the mastermind behind Amy'Leigh's kidnapping.After initially demanding a R2m ransom, her kidnappers abandoned their plan and released the six-year-old girl.The bail application is expected to continue on October 1, when the defence is expected to present its case.