On its face, the Form I-247 sent to the Lyon County Sheriff is not the equivalent of an outstanding warrant for probation revocation, parole violation, or new charges in another jurisdiction. Each of those represents a custodial claim on a defendant's presence to adjudicate existing charges or allegations. The I-247 sent to the Lyon County jail presented the interest of the ICE in clear terms, disclosing that an investigation "has been initiated" and that the ICE would like to know when the defendant was going to be released from custody in Lyon County. The ICE notice in this case is analogous to a call to a sheriff from a law enforcement agency in a neighboring county, expressing interest in one of his or her inmates and asking the sheriff for notice when the inmate is to be released. The request is for cooperation, not custody. It is not particularly helpful that the I-247 form bears the heading "Immigration Detainer--Notice of Action" since, in this case, the "action" was inconsistent with the common custodial use of the term detainer.
The I-247 sent to the Lyon County Sheriff by the ICE represented nothing more than information about the possibility of formal proceedings.
This may make a difference is some other pending cases as well.