The first "逮捕された" is referred to 20代女, so:
逮捕された+20代女 | の | 夫も | 死体遺棄容疑(で)逮捕
The husband of the arrested woman in her 20s was also arrested for dumping the body.
Notice the arrested is used twice.
Hence the first "逮捕された" is needed, but if it had been stated earlier that the woman had been arrested, I think you can omit that. Though, if ...