This varies widely from State to State. I did a lot of research 30 years ago, and was able to get a guy's brand new Pontiac Grand Prix out of impound when the DA reviewed our position. Still a giant headache. I have not handled a civil forfeiture case since, but have always taken note when one pops up. In most cases, NO criminal conviction is required to support the forfeiture.
The history of civil forfeiture is fascinating. It actually has its roots in ecclesiastical law from the middle ages, when they thought that a thing that caused death was inherently evil (such as a runaway wagon, or a horse). Most ordinary citizens couldn't read or write and relied on the church to tell them what was right and wrong, which led to all kinds of abuses. The "thing" would be seized, and either destroyed, or sold and the proceeds used for some pious purpose. The "thing" was classified as deodand (given to God) to supposedly help right the wrong. England abandoned that line of thinking AFTER the Revolutionary War (around 1860 or so), but the US continued to follow. So, even though the English don't practice "deodand" law, we do, as part of the English Common Law. As with many things (not just in the law) the origins are lost to history, and we just keep on going "because that's the way we have always done it."
MOST of the civil cases in the last 50 years have been drug cases, and since the 90's funds used to finance terrorism.
There is some help coming from the US Supreme Court that is going to make it more difficult for States to use this. There may have been an even more helpful case since this one, but I don't have time to research it right now. Looks like the tide may be turning back to common sense.
https://www.vox.com/policy-and-polit...vil-forfeiture
If you want to read an extreme case where a yacht was seized because marijuana was found on board, read this. The owner was in no way involved, and had no way to know that the guys renting the yacht would smoke a joint while there. Great dissent by William O. Douglas.
https://scholar.google.com/scholar_c...=6,37&as_vis=1
You will want to skip the first third of the opinion where they are deciding if a Puerto Rico law is a "state law".