Lutheran theologian Ernst Wilhelm Hengstenberg (1802-1869) believed that the beginning of Daniel’s 70 weeks was the decree issued in the 20th year of Artaxerxes, which he supposed occurred in 455 BC, a date which challenged conventional chronology. In his view, the 70th week was limited to seven literal years, which included the ministry of Jesus, plus the three and a half years that followed. A similar interpretation of the 70th week is favored by many preterists today.
Hengstenberg’s proposed termination of the 70 weeks was not marked
by any significant event. He wrote: 
The extreme point to which this prophecy extends, namely, the period, which was to commence with the complete forgiveness of sins, the bringing in of eternal righteousness, &c., falls precisely at the close of the seventy weeks. But it is a mistake, to make this the basis of chronological calculations; for the simple reason, that it is not marked by any distinct and clearly defined event. Such an event, however, we do find at the end of the sixty-ninth week, namely, Christ’s public appearance, and his anointing with the gifts of the Spirit; and we are the more inclined to take this as the basis of our calculation, just because of the very remarkable fact, that the chronological data, connected with this event, are as carefully recorded in the history of the fulfilment, as they are here in the prophecy itself, and more carefully than in the case of his birth, his resurrection, his ascension, or any other event connected with his life.
Hengstenberg referred to the one week of confirming the covenant as the ministry of Jesus and the preaching of the apostles to the Jews after the resurrection. For Hengstenberg, the 70th week ended in obscurity. He wrote: 
We have shewn, that the last week commences with the public appearance of the anointed one, that his death occurs in the middle of the week, and that the confirming of the covenant occupies the whole of it. All that remains to he done here, is to show how exactly the prophecy and its fulfilment coincide, with reference to one particular point, the death of Christ. The terminal point of the confirmation of the covenant is, more or less, a vanishing one, and therefore does not admit of being chronologically determined, with any minute precision. Suffice it to say, that, in the few years immediately following the death of Christ, the (eklogh) were gathered together, out of the ancient people of the covenant–with what result we may see, for example, in the history of the first day of Pentecost,–and that the gospel of Christ was then carried to the Gentiles; so that the prophet could justly represent salvation, as both objectively and subjectively finished at the end of the seventy weeks, so far as the covenant nation was concerned, to which alone his prophecy referred.
The eklogh refers to the elect or the chosen. An interesting discussion on the word is available, by C. Gordon Olson. 
The scripture does not say that Christ’s death was in the middle of the week, but that the sacrifices and oblations would end in the midst of the week. The vague termination of the 70th week, which distinguishes the preterist interpretation of Daniel’s prophecy was also noted by preterist Kenneth L. Gentry, Jr. He wrote: 
This confirmation of God’s covenant promises to the “many” of Israel will occur in the middle of the seventieth week (v. 27), which parallels “after the sixty-two [and seven] weeks” (v. 26), while providing more detail. We know Christ’s three-and-one-half-year ministry was decidedly focused on the Jews in the first half of the seventieth week (Matt. 10:5b, cf. 15:24). For a period of three and one-half years after the crucifixion, the apostles focused almost exclusively on the Jews, beginning first “in Judea” (Acts 1:8; 2:14) because “the gospel of Christ” is “for the Jew first” (Rom. 1:16, cf. 2:10; John 4:22).
Although the event that serves as the terminus of the sixty-ninth week is clearly specified, such is not the case with the terminus of the seventieth. Thus, the exact event that ends the seventieth is not so significant for us to know. Apparently at the stoning of Stephen, the first martyr of Christianity, the covenantal proclamation began to be turned toward the Gentiles (Acts 8:1). The apostle to the Gentiles appears on the scene at Stephen’s death (Acts 7:58–8:1) as the Jewish persecution against Christianity breaks out. Paul’s mission is clearly stated as exceeding the narrow Jewish focus (Acts 9:15).
The following are some objections to the preterist interpretation of Hengstenberg and Gentry.
The seventy weeks correspond to three of the four periods of seven times in Lev. 26
1. Ernst Wilhelm Hengstenberg. Christology of the Old Testament. Volume 3. pp. 202-203.
3. C. Gordon Olson. Astounding New Greek Discoveries about ‘Election’
4. Kenneth L. Gentry, Jr. Daniel’s Seventy Weeks and Biblical Prophecy